are dissertations grey literature

• Research Guides

Grey Literature

• What is Grey Literature? Activities
• Why Use Grey Literature?
• Types of Grey Literature
• Sources of Grey Literature
• Searching for Grey Literature
• Evaluating Grey Literature Activity
• How to Incorporate & Cite Grey Literature

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This guide includes content adapted with permission from the University of Illinois Library .

What is Grey Literature?

Describing grey literature in its entirety is more challenging than outlining what it isn't. Grey literature encompasses various media, resources, documents, and data that diverge from the conventional academic or commercial publishing pathways, often termed "white literature." If a resource lacks publication in a scholarly journal, it likely falls within the realm of grey literature. Unlike white literature, grey Literature doesn't undergo peer review and typically avoids publication in books or scholarly journals. Today, most grey literature is disseminated digitally through PDFs, web pages, blog posts, and multimedia content. Unlike academic publishing, grey literature authors are not required to possess extensive field experience, though recognized experts or organizations often author the most credible pieces. Grey literature spans a broad spectrum—it's not necessarily always factual or nonfactual, nor is it constrained to a purely professional or casual tone.

• A local government's report on the city's water quality
• The front page news story from a national news company***
• An engineering PhD candidate's dissertation on keyword latency  
• The state government's crime statistics from the last year
• A pamphlet from the Forest Service on the history of a national park
• A report from an international non-governmental organization (NGO) on modern slavery
• A blog post from a well-known academic on a new theory concerning her field
• Tweets from protestors involved in the Arab Spring demonstrations 
• Court transcripts and other legal documents

All these items can be helpful in research, but using, evaluating, and finding good grey literature can be challenging. This guide is designed to help users understand and navigate the complexities of this special literature. 

***Some do not consider news grey literature because it comes from a commercial publishing system. Still, others do because it is not peer-reviewed or necessarily written by experts in the field. This guide includes news media as grey literature because it is not peer-reviewed and can be evaluated using the same methods as grey literature.

What is "Scholarly" and "Peer Reviewed"?

Scholarly sources (also referred to as academic, peer-reviewed, or refereed sources) are written by experts in a particular field and keep others interested in that field up to date on the most recent research, findings, and news.

When a source has been peer-reviewed, it has undergone the review and scrutiny of a review board of colleagues in the author’s field. They evaluate this source as part of the body of research for a particular discipline and make recommendations regarding its publication in a journal, revisions before publication, or, in some cases, reject its publication.

In essence, when a work is scholarly and peer-reviewed, the work of evaluating a resource is done by the publisher, and the resource user does not have to spend too much time evaluating it themselves. This is extremely useful as it ensures the information is factual. However, the process of peer review is far from perfect; it has its own set of biases and issues with diversity; it is a lengthy process, and scholarly and peer-reviewed works are often expensive to access.

When resources are not peer-reviewed, the work of evaluating the resources falls almost entirely on the user. Grey literature is typically only reviewed for accuracy by their organization, and the process varies widely from organization to organization if they have one at all. The users reading the information cannot be sure if anyone has reviewed the facts presented in grey literature and if the organizations' biases have distorted the facts.  

Activity: What is Grey Literature?

Use the interactive module below to test your knowledge of grey literature!

Activity: Grey Literature Drag and Drop

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Systematic reviews & evidence synthesis methods.

• Schedule a Consultation / Meet our Team
• What is Evidence Synthesis?
• Types of Evidence Synthesis
• Evidence Synthesis Across Disciplines
• Finding and Appraising Existing Systematic Reviews
• 0. Develop a Protocol
• 1. Draft your Research Question
• 2. Select Databases
• 3. Select Grey Literature Sources
• 4. Write a Search Strategy
• 5. Register a Protocol
• 6. Translate Search Strategies
• 7. Citation Management
• 8. Article Screening
• 9. Risk of Bias Assessment
• 10. Data Extraction
• 11. Synthesize, Map, or Describe the Results
• Open Access Evidence Synthesis Resources

Grey Literature

Grey literature is literature produced by individuals or organizations outside of commercial and/or academic publishers. This can include information such as government reports, conference proceedings, graduate dissertations, unpublished clinical trials, and much more. The sources you select will be informed by your research question and field of study, but should likely include, at a minimum, theses and dissertations.

Why Search the Grey Literature?

The intent of an evidence synthesis is to synthesize all available evidence that is applicable to your research question. There is a strong bias in scientific publishing toward publishing studies that show some sort of significant effect. Meanwhile, many studies and trials that show no effect end up going unpublished. But knowing that an intervention had no effect is just as important as knowing that it did have an effect when it comes to making decisions for practice and policy-making. While not peer-reviewed, grey literature represents a valuable body of information that is critical to consider when synthesizing and evaluating all available evidence.

Searching the Grey Literature

Finding grey literature and searching it systematically is challenging. But there are a few approaches that you can take to add some structure to your search of this type of information:

• Refer to grey literature sources used for related evidence syntheses. Refer to both published evidence syntheses and registered protocols.
• Ask experts in the field for relevant grey literature sources. If you are an expert, include important grey literature sources, and ask colleagues for their recommendations.
• Search databases that specialize in grey literature: See the "Grey Literature Sources" box at the bottom of this page for more information.
• Search for theses and dissertations: There are a number of databases dedicated to theses and dissertations, which you can search using your search terms. See the "Grey Literature Sources" box at the bottom of this page for links to these resources.
• Search clinical trials: There may be clinical trials being conducted that are relevant to your research question, but that haven't been published yet or never were published. See the "Grey Literature Sources" box at the bottom of this page for links to these resources.
• Identify government agencies and international and non-governmental organizations that might publish technical papers and reports on your topic. Search their websites or any online libraries that they may provide. See the "Grey Literature Sources" box at the bottom of this page for links to some examples.
• Search conference proceedings and newsletters: Identify professional organizations that have and/or conferences at which researchers might be presenting work related to your topic. Search those conference proceedings or newsletters on the organization's website or by contacting organizational boards for access to past proceedings that may not be online. See the "Grey Literature Sources" box at the bottom of this page for some examples.
• Contact known researchers in the field to determine if there are any ongoing or unpublished studies that s/he may be aware of.
• Search professional and trade magazines. Professional magazines contain literature that is written by professionals in the field for other professionals in the field, but that may not be about research. Trade magazines contain advertisements and news very specific to a topic or industry.

How to Manage the Grey Literature Search

• Identify and record the sources you will search. The sources you search will be informed by your research question and where you expect to find information related to your question.
• Document where you are searching and your search strategies, including document resource name, URL, search terms, and date searched.
• Collect citation information as you go.
• Adhere to your established inclusion and exclusion criteria when selecting sources.

See below for guidance documents specific to grey literature searching.

Grey Literature Sources

• Grey Literature Databases
• Theses and Dissertations
• Clinical Trials
• Public Policy
• Conference Proceedings
• Preprint Repositories
• Other Resources
• NY Academy of Medicine Grey Literature Report This report is a bimonthly publication of The New York Academy of Medicine (NYAM) alerting readers to new grey literature publications in health services research and selected public health topics. The database platform is keyword searchable and serves as an archive for the cataloged reports.
• WHO Library Database The WHO library database includes governing documents, reports and technical documentation.
• Global Think Tanks A database of reports, papers, and other resources published by NGOs, think tanks, IGOs and research centers from across the world. It also includes a directory of thousands of organizations involved in public and social policy in most subject area. A module in the Policy Commons database.
• MedNar MedNar searches across more than 60 medical research sources, including commercial databases, medical societies, NIH resources, and other government resources.
• Global Index Medicus The Global Index Medicus (GIM) provides worldwide access to biomedical and public health literature produced by and within low-middle income countries. The main objective is to increase the visibility and usability of this important set of resources. The material is collated and aggregated by WHO Regional Office Libraries on a central search platform allowing retrieval of bibliographical and full text information.
• National Grey Literature Collection - UK Funded by Health Education England this holds the catalogue for the hard copy grey literature collection of the former North Grey Literature Service. It is collecting an increasing range of electronic Grey Literature.

• Networked Digital Library of Theses and Dissertations (NDLT) Free international resource for theses and dissertations.
• Center for Research Libraries A resource for institutions outside of the U.S. and Canada.
• EThOS Electronic Theses Online Service contains doctoral theses from candidates in the UK.
• Open Access Theses and Dissertations Resource for finding open access graduate theses and dissertations published around the world. Metadata (information about the theses) comes from over 1100 colleges, universities, and research institutions. OATD currently indexes over 4 million theses and dissertations.
• DART European - Digital Access to Research Theses Europe The aim of DART is to provide researchers with a single European Portal for the discovery of Electronic Theses and Dissertations (ETDs). Note that only theses available in electronic form are included.
• Australia New Zealand Clinical Trials Registry Online register of clinical trials being undertaken in Australia, New Zealand and elsewhere. The ANZCTR includes trials from the full spectrum of therapeutic areas of pharmaceuticals, surgical procedures, preventive measures, lifestyle, devices, treatment and rehabilitation strategies, and complementary therapies.
• ClinicalTrials.gov The US registry for clinical trials. Includes new, ongoing, and completed human clinical trials both in the US and countries around the world.
• Cochrane Central Register of Controlled Trials A highly concentrated source of reports of randomized and quasi-randomized controlled trials. The majority of CENTRAL records are taken from bibliographic databases (mainly MEDLINE and Embase), but records are also derived from other published and unpublished sources.
• EU Clinical Trials Register The European Union Clinical Trials Register allows you to search for protocol and results information on interventional clinical trials that are conducted in the European Union (EU) and the European Economic Area (EEA) and clinical trials conducted outside the EU / EEA that are linked to European paediatric-medicine development.
• WHO International Clinical Trials Registry Platform ICTRP provides access to a central database containing the trial registration data sets provided by numerous international registries. It also provides links to the full original records.
• Wikipedia Clinical Trial Registries List This Wikipedia entry contains a list of links to individual clinical trial registries by country.
• WHO Institutional Repository for Information Sharing (IRIS) Institutional WHO database of intergovernmental policy documents and technical reports. Can search by IRIS by region (Africa, Americas, Eastern Mediterranean, Europe, South-East Asia, Western Pacific).
• Health Research Web A wiki with descriptors of national health research systems, ethics review committees, local and regional policies and research priorities and more.

This list of conference proceedings is not comprehensive, but are ideas of where to search. We recommend that you search proceedings for the three most relevant conferences for your evidence synthesis.

• OCLC PapersFirst OCLC PapersFirst is an OCLC index of papers presented at conferences worldwide.
• BIOSIS Previews A subcollection of Web of Science, BIOSIS Previews searches across journals, meetings, patents, and books in the life sciences and biomedical fields.

• arXiv arXiv is a free distribution service and an open-access archive for scholarly articles in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance, statistics, electrical engineering and systems science, and economics.
• medRxiv medRxiv (pronounced "med-archive") is a free online archive and distribution server for complete but unpublished manuscripts (preprints) in the medical, clinical, and related health sciences.
• PsyArXiv A free preprint service for the psychological sciences. It is maintained by The Society for the Improvement of Psychological Science.
• OSF Preprints A general preprint repository that covers architecture, business, engineering, life sciences, physical sciences and mathematics, arts and humanities, education, law, medicine and health sciences and social and behavioral sciences, among others.
• TechRxiv Hosted by IEEE
• Engineering Archive Created in 2016. Accepts all types of manuscripts, including but not limited to systematic reviews, hypotheses, ‘negative’ results, and data and methods papers.Includes 2 major types of articles: (1) Preprints of articles in parallel to traditional journal submissions. (2) Previously published articles that you wish to make Open Access
• Preprints.org This is a multidiscipline platform providing preprint service that is dedicated to making early versions of research outputs permanently available and citable. We post original research articles and comprehensive reviews, and papers can be updated by authors as long as the updated content has not been published online.
• Grey Matters: A practical search tool for evidence-based medicine This online manual provides a thorough list of sources for grey literature in medicine and a helpful checklist to help systematize your process.
• Searching the grey literature: A handbook for searching reports, working papers, and other unpublished research Searching the Grey Literature is for librarians and information professionals interested in learning more about grey literature. This book will aid with crafting a grey lit search successfully, from start to finish. Many types of librarians will find the content of this book useful, particularly those in health or social science.
• Duke University Medical Center Guide to Resource for Searching the Grey Literature Resources for trial registries, pharmacological studies, conference abstracts, government document and more.
• Gray Literature Resources for Agriculture Evidence Syntheses This is a comprehensive list of agricultural grey literature sources, one of several evidence synthesis worksheets and tools provided to help in non-medical evidence synthesis development and implementation.
• Searching for studies: A guide to information retrieval for Campbell Systematic Reviews This document gives comprehensive guidance in searching for evidence syntheses, and offers a robust list of grey literature sources for social science disciplines.
• Finding Grey Literature Evidence and Assessing for Outcome and Analysis Reporting Biases When Comparing Medical Interventions: AHRQ and the Effective Health Care Program An introduction to clinical resources and strategies in approaching systematic reviews.

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Reference management. Clean and simple.

What is grey literature? [with examples]

What's the importance of grey literature?

What are some of the drawbacks of grey literature, what are some examples of grey literature, how do you identify grey literature, where can you search for grey literature, are there any other ways to find grey literature, use search engines, go directly to organizations' websites, contact researchers directly, frequently asked questions about grey literature, related articles.

Grey literature refers to materials and research published specifically outside of the traditional commercial, academic publishing, and distribution channels.

It is produced by organizations on all levels of government, academia, business, and industry and either published informally or remains unpublished. Not every grey literature database will have undergone the peer review process due to this informal setup, but the information contained therein can still prove valuable to researchers and academics alike - if they are able to find it.

Since grey literature usually comes from multiple sources, finding the right resource can prove to be challenging. It's not as simple as visiting a library. With no indexes or formal organization, grey literature won't appear in academic sources like books or journals. But the question still remains, what is grey literature and why is it important to academic publishing?

• Grey literature is often the best source for up-to-date research on certain topics. This is because it doesn't have to go through the often lengthy process of publication before it can be reviewed.
• In the same breath, grey literature databases can have a scope that includes recently emerging areas of research.
• Scientific publishing, for instance, has a strong bias toward publishing research that shows a significant positive correlation. Many studies show no effect and can go unpublished, but negative results are just as important to note. Accessing grey literature fills this knowledge gap, and generates a more balanced picture of the available evidence.
• The reports produced in grey literature are often more detailed in nature and can contain raw data sets not available anywhere else - the caveat is that they come in tons of different formats and document types, making the data slightly more difficult to find.
• Grey literature can help researchers to reduce publication bias.
• Most grey literature is free (one exception is materials produced by market research firms, who often charge for access). This makes it a lot more accessible to everyone.
• The information in grey literature hasn't gone through the usual publishing channels, so it isn't rigorously and formally peer-reviewed. This means you'll need to carry out your own checks to assess its reliability.
• When grey literature isn't published, it's free from publication bias. However, it may carry its own set of biases. The organization that distributed the grey literature can have its own political, social, or financial motivations for promoting unreliable research. Make sure to cross-check information from grey literature against studies found elsewhere.
• Grey literature is produced from a great variety of sources, so it's usually not indexed or organized in any way. That can make it very difficult to locate what you're looking for.
• Librarians often have a difficult time acquiring grey literature and making it accessible.

Publication types of grey literature are almost endless, and include:

• Government reports
• Technical reports
• Unpublished clinical trials
• Conference abstracts
• Graduate dissertations and theses
• Newsletters
• White papers
• Working papers
• Dissertations

Websites, manuals, statistics, and datasets are technically also types of grey literature that you may come across during the research process.

Grey literature can be found in so many contexts it can be tough to list them all. Essentially, if you didn't find it in a renowned journal or published book, there's a good chance it's grey literature. Luckily, if you know how to find academic sources, you should be able to identify grey literature in the wild.

Here are some other indicators that you may be looking at a piece of grey literature:

• It was difficult for you to find
• It hasn't been widely distributed
• It contains more information on the subject than you've seen elsewhere, as there weren't publication length stipulations
• It was produced and disseminated quickly
• It hasn't been archived

It can be difficult to develop a systematic approach to finding grey literature for academic purposes. Unlike scholarly journals that are often available in electronic formats, grey literature databases will be all over the map in terms of formats and accessibility.

You should prepare any search terms you're going to use, identify the ones that are most applicable, and record the sources as you search. If you have a research question, use it to guide where you look for the sources you're going to search.

There are also many grey literature databases that specialize in cataloging grey literature:

There are methods that you can make use of to target your search for grey literature.

• Restrict content to only governments or organizations by typing in your search term and then either 'site:.org' or 'site:.gov'.
• You can take it further and limit your search to e.g. UK government sites only by typing 'site:.gov.uk'.
• Restrict content to a specific file type by typing in your search term and then e.g. 'filetype:pdf' or 'filetype:doc'.
• If you're looking for grey literature from a specific country, use their version of Google, for example, Google Australia or Google UK .
• If you'd like a fresh take, try search engine DuckDuckGo , as it doesn't track location or user searches. This means it doesn't filter results based on your user profile.

Identify organizations that might publish technical papers and reports on the subject you're looking for. These could be government agencies, non-profits, research institutes, pressure groups, international organizations, or professional associations.

For example, the World Health Organization (WHO) has several online collections of grey literature and the World Bank makes all of their publications available online for free.

Search your chosen organizations' websites, looking for sections of the site with names such as 'Documents', 'Reports' or 'Library'.

Research known researchers in your field of interest. You can then contact them to kindly ask if they're aware of any unpublished or ongoing studies - more often than not they will be happy to point you in the right direction.

Grey literature is materials and research that have been published specifically outside of the traditional commercial or academic publishing and distribution channels. The term 'grey' refers to the uncertainty of the status of this information.

Yes, preprints are considered grey literature, as they have not undergone the peer-review process.

PubMed is a research database, not a publication type. Material indexed by major databases such as PubMed is generally not considered grey literature.

Books and other scholarly publications have to pass through a formal publishing process and are therefore not considered grey literature.

Yes, dissertations are generally considered grey literature and might be hard to obtain in some cases.

Grey literature: An important resource in systematic reviews

Affiliation.

• 1 Nuffield Department of Primary Care Health Sciences, Centre for Evidence-Based Medicine, Department for Continuing Education, The University of Oxford, Oxford, UK.
• PMID: 29266844
• DOI: 10.1111/jebm.12265

Systematic reviews aid the analysis and dissemination of evidence, using rigorous and transparent methods to generate empirically attained answers to focused research questions. Identifying all evidence relevant to the research questions is an essential component, and challenge, of systematic reviews. Grey literature, or evidence not published in commercial publications, can make important contributions to a systematic review. Grey literature can include academic papers, including theses and dissertations, research and committee reports, government reports, conference papers, and ongoing research, among others. It may provide data not found within commercially published literature, providing an important forum for disseminating studies with null or negative results that might not otherwise be disseminated. Grey literature may thusly reduce publication bias, increase reviews' comprehensiveness and timeliness and foster a balanced picture of available evidence. Grey literature's diverse formats and audiences can present a significant challenge in a systematic search for evidence. However, the benefits of including grey literature may far outweigh the cost in time and resource needed to search for it, and it is important for it to be included in a systematic review or review of evidence. A carefully thought out grey literature search strategy may be an invaluable component of a systematic review. This narrative review provides guidance about the benefits of including grey literature in a systematic review, and sources for searching through grey literature. An illustrative example of a search for evidence within grey literature sources is presented to highlight the potential contributions of such a search to a systematic review. Benefits and challenges of grey literature search methods are discussed, and recommendations made.

Keywords: evidence; grey literature; publication bias; search; systematic review.

© 2017 Chinese Cochrane Center, West China Hospital of Sichuan University and John Wiley & Sons Australia, Ltd.

Grey Literature: Dissertations & Theses

• Clinical Trials
• Research Registries
• Drug & Device
• Results Databases
• Conference Proceedings
• Proceedings Databases

Dissertations & Theses

• OA Resources
• Reports & Reviews

Dissertations and Theses are considered grey literature. These resources can be found in many different places: Databases, websites, catalogs and WorldCat (combination of catalog/database). 

Dissertations and Theses Resources:

American Doctoral Dissertations

• DART Europe
• Electronic Theses & Dissertations Center (ETD)
• Networked Digital Library of Theses and Dissertations (NDLTD)
• Open Access Theses and Dissertations (OATD)
• ProQuest Dissertations & Theses
• TCU Library Electronic Theses & Dissertations

The database includes more than 153,000 theses and dissertations in total, including 70,000 new citations for theses and dissertations. The new citations include a link to access the full text, when available, via the Institutional Repository where the thesis or dissertation is housed.

Dart Europe

DART-Europe is a partnership of research libraries and library consortia who are working together to improve global access to European research theses.

Electronic Theses & Dissertations Center (ETD)

The ETD Center is a free, online database of Ohio's undergraduate, masters and doctoral theses and dissertations from participating OhioLINK member schools. It contains the abstract for all included theses and dissertations. The full-text is also available if it was submitted.

Networked Digital Library of Theses and Dissertations

Started by Virginia Tech University, this is a global database of over 750,000 ETDs (electronic theses and dissertations).

Open Access Theses & Dissertations

OATD.org aims to be the best possible resource for finding open access graduate theses and dissertations published around the world. Metadata (information about the theses) comes from over 1100 colleges, universities, and research institutions. OATD currently indexes 3,897,764 theses and dissertations.

PQDT Open provides the full text of open access dissertations and theses free of charge.

You can quickly and easily locate dissertations and theses relevant to your discipline, and view the complete text in PDF format.

ProQuest Dissertations & Theses

ProQuest Dissertations & Theses Global searches millions of dissertations and theses from around the world, and has over one million dissertations in full text.

TCU Electronic Theses and Dissertations

Searchable Collections from the TCU Community.

OCLC's WorldCat lists dissertations for most colleges and universities in the United States and Canada and a great many from around the world. 

The free version of WorldCat can be found here .

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• Last Updated: Oct 13, 2021 9:05 AM
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Public Health: Defining Grey Literature

• Getting Started
• Public Health Books in the Library
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• How to Search Scholarly Databases
• How to Search for Textbooks & Other References
• Defining Grey Literature
• Key Sources & Databases for Grey Literature
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Guidance Documents for Searching Gray Literature

• Grey Matters: A Practical Search Tool for Evidence-Based Medicine This online manual provides a thorough list of sources for gray literature in medicine and a helpful checklist to help systematize your process.
• Googling the Greys: Tips for Searching Beyond Health Databases and Turning Information into Insights This PDF presentation by Sarah Bonato, a health science librarian at the Centre for Addiction and Mental Health in Toronto, ON, provides an excellent guide to searching Google effectively to find gray literature.
• Duke University Medical Center Guide to Resource for Searching the Gray Literature A more thorough guide to gray literature, including resources for trial registries, pharmacological studies, conference abstracts, government document and more.

What Grey Literature Is -- and How to Search It

What is grey literature?   Grey (or gray) literature is defined by the  Cochrane Handbook for Systematic Reviews of Interventions  as "...literature that is not formally published in sources such as books or journal articles." This can include information such as government reports, conference proceedings, graduate dissertations, unpublished clinical trials, and much more.  

Why search the grey literature if it hasn't been peer-reviewed?   There is a strong bias in scientific publishing toward publishing studies that show some sort of significant effect.  Meanwhile, many studies and trials that show no effect end up going unpublished.  But knowing that an intervention had no effect is just as important as knowing that it did have an effect when it comes to making decisions for practice and policy-making.  Thus, the grey literature can be critical.

How do I search the grey literature if it's unpublished and not in the scholarly databases?    Its true--finding grey literature and searching it systematically is challenging.  But there are a few approaches that you can take to add some structure to your search of this type of information:

• Identify and record  the sources you will search, including some indication of search terms used if appropriate.  The sources you search will be informed by your research question and where you expect to find information related to your question.
• Try searching  databases that specialize in grey literature  like  OpenGrey .  See the box below for more information.
• Conference proceedings :  Identify professional organizations that have conferences at which researchers might be presenting work related to your topic.  Search those conference proceedings on the organization's website or by contacting organizational boards for access to past proceedings that may not be online.
• Theses and dissertations :  There are a number of databases dedicated to theses and dissertations, which you can search using your search terms.  See the box below for links to these resources. 
• Identify government agencies, and international and non-governmental organizations , that might publish technical papers and reports on your topic.  Search their websites or any online libraries that they may provide.  For example, the  WHO  has a number of searchable online collections and the  World Bank  now makes all of their publications openly available online.
• Contact known researchers  in the field to determine if there are any ongoing or unpublished studies that s/he may be aware of.
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• Next: Key Sources & Databases for Grey Literature >>
• Last Updated: Jan 24, 2024 1:52 PM
• URL: https://guides.library.cornell.edu/public-health

Evidence Synthesis: Finding, appraising and synthesizing research

• Getting Started
• Steps in Evidence Synthesis
• Methodology and Documentation
• Searching the published literature
• Searching the Gray Literature
• Managing the process

The gray literature: What is it and how do I search it?

Why search the gray literature if it hasn't been peer-reviewed?   There is a strong bias in scientific publishing toward publishing studies that show some sort of significant effect.  Meanwhile, many studies and trials that show no effect end up going unpublished.  But knowing that an intervention had no effect is just as important as knowing that it did have an effect when it comes to making decisions for practice and policy-making.  Thus, the grey literature can be critical.

How do I search the gray literature if it's unpublished and not in the scholarly databases?  Its true--finding gray literature and searching it systematically is challenging.  But there are a few approaches that you can take to add some structure to your search of this type of information:

• Identify and record the sources you will search, including some indication of search terms used if appropriate.  The sources you search will be informed by your research question and where you expect to find information related to your question.
• Try searching databases that specialize in gray literature like OpenMD , MedNar and BASE . OpenGrey , a previously available resource for gray literature, is also searchable from a locally maintained SQL database.  For more resources, see the box below.
• Conference proceedings :  Identify professional organizations that have conferences at which researchers might be presenting work related to your topic.  Search those conference proceedings on the organization's website or by contacting organizational boards for access to past proceedings that may not be online.
• Theses and dissertations :  There are a number of databases dedicated to theses and dissertations, which you can search using your search terms.  See the box below for links to these resources. 
• Identify government agencies, and international and non-governmental organizations , that might publish technical papers and reports on your topic.  Search their websites or any online libraries that they may provide.  For example, the WHO has a number of searchable online collections and the World Bank now makes all of their publications openly available online.
• Contact known researchers in the field to determine if there are any ongoing or unpublished studies that s/he may be aware of.

Image credit:  Stack 'em high, by Antony Theobald via Flickr.com, https://flic.kr/p/6WW7E2, CC BY-NC-ND 2.0

Guidance documents for gray literature searching

• Grey Matters: A practical search tool for evidence-based medicine This online manual provides a thorough list of sources for gray literature in medicine and a helpful checklist to help systematize your process.
• Googling the Greys: Tips for Searching Beyond Health Databases and Turning Information into Insights This presentation by Sarah Bonato, a health science librarian at the Centre for Addiction and Mental Health in Toronto, ON, provides an excellent guide to searching Google effectively to find gray literature.
• Duke University Medical Center Guide to Resource for Searching the Gray Literature A more thorough guide to gray literature, including resources for trial registries, pharmacological studies, conference abstracts, government document and more.

Databases of grey literature

• BASE BASE is one of the world's most voluminous search engines especially for academic web resources. BASE provides more than 240 million documents from more than 8,000 content providers. You can access the full texts of about 60% of the indexed documents for free (Open Access). BASE is operated by Bielefeld University Library.
• MedNar Mednar is a free, medically-focused deep web search engine that uses Explorit Everywhere!, an advanced search technology by Deep Web Technologies. As an alternative to Google, Mednar accelerates your research with a search of authoritative public and deep web resources, returning the most relevant results to one easily navigable page.
• NY Academy of Medicine Grey Literature Report This report was a bimonthly publication of The New York Academy of Medicine (NYAM) alerting readers to new grey literature publications in health services research and selected public health topics. The report is no longer being maintained but some of the resources are still accessible.
• OpenMD OpenMD.com is a search engine that makes high-quality medical information easily accessible to everyone. OpenMD searches billions of documents from government agencies, global health organizations, medical journals, and reference sites.

Sources for searching theses and dissertations

• ProQuest Dissertations and Theses With more than 2 million entries, PQD&T is the single, central, authoritative resource for information about doctoral dissertations and master's theses.

Resources for Clinical Trials

• Australia New Zealand Clinical Trials Registry Online register of clinical trials being undertaken in Australia, New Zealand and elsewhere. The ANZCTR includes trials from the full spectrum of therapeutic areas of pharmaceuticals, surgical procedures, preventive measures, lifestyle, devices, treatment and rehabilitation strategies and complementary therapies.
• ClinicalTrials.gov The US registry for clinical trials. Includes new, ongoing and completed human clinical trials both in the US and in countries around the world.
• Cochrane CENTRAL Register A highly concentrated source of reports of randomised and quasi-randomised controlled trials. The majority of CENTRAL records are taken from bibliographic databases (mainly MEDLINE and Embase), but records are also derived from other published and unpublished sources.
• EU Clinical Trials Register The European Union Clinical Trials Register allows you to search for protocol and results information on interventional clinical trials that are conducted in the European Union (EU) and the European Economic Area (EEA) and clinical trials conducted outside the EU / EEA that are linked to European paediatric-medicine development.
• WHO International Clinical Trials Registry Platform (ICTRP) This Clinical Trials Search Portal provides access to a central database containing the trial registration data sets provided by numerous international registries. It also provides links to the full original records.
• Wikipedia clinical trial registries list This Wikipedia entry contains a list of links to individual clinical trial registries by country.
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Systematic reviews and other evidence synthesis projects

• Types of Reviews
• Systematic Reviews
• 0. Plan your Review
• 1. Define the Question
• 2. Check for Recent Systematic Reviews and Protocols
• 3. Write and register your protocol
• Developing your Search Terms
• Database Search Tips and Filters
• Grey Literature

What is grey literature?

Clinical trials, reports and research, dissertations & theses at uw and beyond, other materials, institutional repositories, igo/ngo search engines, grey literature in the databases.

• Record and Report your Search Strategy
• Covidence This link opens in a new window
• 6. Appraise the Studies
• 7. Extract Data
• 8. Analyze / Synthesize Data
• 9. Write the Review
• Rapid Reviews
• Scoping Reviews
• Equity in Evidence Synthesis
• Automation, AI, and other upcoming review technologies
• Librarian Support

Grey literature is generally material not published commercially or indexed by major databases. 

A more complete definition is information "produced on all levels of government, academics, business and industry in electronic and print formats not controlled by commercial publishing i.e. where publishing is not the primary activity of the producing body." ( http://www.greynet.org/ )

It may include: Reports, preprints, working documents, research papers, theses and dissertations, clinical trial registrations, bibliographies, newsletters, patents, statistical documents, white papers, pamphlets, datasets, informal communication (e.g., blogs, podcasts, email), and more.

The most appropriate grey literature for your review will depend on your research topic. Not all of the possible sources listed below will apply. To develop the most relevant grey literature search strategy for your project, consider:

• Government agencies?
• Non-governmental organizations?
• Academic institutions?
• Clinical trials?
• Theses and dissertations?
• Conference proceedings?
• Statistics?
• Which time periods or geographic areas are relevant to your research?

More about grey literature from the Cochrane Handbook for Systematic Reviews of Interventions

Why include grey literature?

The intent of a systematic review is to synthesize all available evidence that is applicable to your research question. Cochrane's Methodological Expectations for Cochrane Intervention Reviews standards recommends that authors: "Search relevant grey literature sources such as reports, dissertations, theses, databases and databases of conference abstracts. Searches for studies should be as extensive as possible in order to reduce the risk of publication bias and to identify as much relevant evidence as possible."

Material in the grey literature may be:

• a better source of information on policies and programs
• trials indicating no effect or negative results, which are less likely to be published than positive results
• a source of different perspectives than major publications offer
• more current, with better coverage of emergent research areas
• more detailed than journal articles, with raw data or more extensive context

The Agency for Healthcare Research and Quality describes reasons and methods for including grey literature in " Finding Grey Literature Evidence and Assessing for Outcome and Analysis Reporting Biases When Comparing Medical Interventions: AHRQ and the Effective Health Care Program ."

Remember to record your search strategy for your grey literature searches too!

• Identify and record the sources you will search. The sources you search will be informed by your research question and where you expect to find information related to your question.
• Document where you are searching and your search strategies, including document resource name, URL, search terms, and date searched.
• Collect citation information as you go.
• Adhere to your established inclusion and exclusion criteria when selecting sources.
• CenterWatch : Global source for clinical trials information, offering news, analysis, study grants, career opportunities, and trial listings to professionals and patients
• ClinicalTrials.gov: Registry and results database of federally and privately supported clinical trials conducted in the United States and around the world
• EU Clinical Trials Register:  Registered clinical trials in the European Union 
• ISRCTN Register: Registered randomized controlled trials and other studies to assess the efficacy of health care interventions around the world 
•   ICTRP : The WHO International Clinical Trials Registry Platform searches in clinicaltrials.gov and the ISRCTN Register along with 16 other international clinical trials registries.
• National Technical Reports Library (NTRL): Source for U.S. government-funded scientific, technical, engineering, and business reports from more than 200 U.S. government agencies
• NIH RePORTER : Describes research projects funded by NIH and other DHHS agencies.
• Patient-Centered Outcomes Research Institute (PCORI) : Studies on comparative clinical effectiveness research focusing on outcomes important to patients
• National Research Register (NRR) Archive:    research from England
• Sigma Nursing Repository (formerly known as the Virginia Henderson International Nursing Library)  Virginia Henderson International Nursing Library--Registry of Nursing Research -->
• Virtual Technical Reports Center : List of institutions with links to technical reports, preprints, eprints, reprints, dissertations, theses, and research reports of all kinds
• WHO Institutional Repository for Information Sharing (IRIS) : Institutional WHO database of intergovernmental policy documents and technical reports. Can search by IRIS by region (Africa, Americas, Eastern Mediterranean, Europe, South-East Asia, Western Pacific).
• WHO Library Database : The WHO library database includes governing documents, reports and technical documentation.

A preprint is a version of a scholarly or scientific manuscript that has not gone through the formal peer review, editing, or journal-publishing process. While a manuscript might be only in preprint status due to poor research or writing, there are also reasons unrelated to quality. These include publication bias¹, submitting to journals based on reputation rather than subject matter match, and the time required for peer review.²

Researchers might choose to include preprints for topics that are under-studied, novel, or rapidly-changing. For example, over 30,000 preprints on COVID-19 were hosted on preprint servers between January 1, 2020 and October 31, 2020 as researchers raced to address the pandemic.³

Sources for preprints:

• medRxiv - Medical and Health Sciences Preprints
• bioRxiv - Biology Preprints
• Europe PMC - search includes medRxiv, bioRxiv, and several other preprint sources--use Advanced Search and select Preprint records from filters
• SocArXiv (OSF) - Social Sciences Preprints.
• PsyArXiv (OSF) - Psychology Preprints
• Preprints.org - Multidisciplinary preprint server associated with Web of Science
• SSRN: Social Science Research Network - Research Networks in Multiple Disciplines

³Fraser N, Brierley L, Dey G, et al. The evolving role of preprints in the dissemination of COVID-19 research and their impact on the science communication landscape. PLoS Biol . 2021;19(4):e3000959. Published 2021 Apr 2. doi:10.1371/journal.pbio.3000959. PMID: 33798194 .

• ResearchWorks at the UW Browse collections of UW communities including Dissertations and Theses, Faculty Researcher Data and Papers, Student Research Papers.
• Guide to finding dissertations & theses at UW and beyond
• TRIP Database Images, videos, patient information leaflets, educational courses and news; also articles.

An  Institutional Repository is a virtual space where a university or research institute collects and preserves its research and findings. Information in Repositories is considered grey literature since these resources are not traditionally published.

• ResearchWorks at the University of Washington: digital repository of articles, technical reports, dissertations, datasets, images and other file types produced at UW by faculty and researchers.
• OpenDOAR : directory of open access repositories

Use the search engines below to search keywords across many IGO (inter-governmental organization) or NGO (non-governmental organization) websites. For example, a single search for "microfinance" using the Union of International Associations IGO search will find reports and research on this topic from USAID, World Bank, Asian Development Bank, and many more.

• Union of International Associations IGO Search Custom Google search of the websites of all intergovernmental organizations (IGOs), comprising over 3000 bodies including the United Nations, the European Commission, the World Bank, etc.
• Intergovernmental Organizations Custom Google search across hundreds of intergovernmental organization websites. From American Library Association's Government Documents Round Table (GODORT).
• Non-Governmental Organizations Custom Google search across hundreds of non-governmental organization websites. From American Library Association's Government Documents Round Table (GODORT). More information on coverage of GODORT searches at: http://www.ala.org/rt/godort/taskforces/internationaldocuments/idtf/igo-search

When using these searches or other custom Google searches, you can apply the methods from the Google Searching section to create complex queries. Google does not offer the same kind of control as the subscription databases do, but these tips can help you build searches that approximately correspond with your database searches.

Tip: At first it will appear that you have thousands of results. However, if you page through them there will actually be only a few pages.

The Deep Web, also known as the Invisible Web , is a portion of the web not reached by standard search engines, such as Google and Bing. Less than 10% of the web is indexed by search engines, with the remaining 90% of web content called the Deep Web. It is estimated to be 2-500x bigger than the visible web. 

Here are some general resources to search the Deep Web:

• Grey Matters: A practical search tool for evidence-based medicine
• Kennedy School of Government Think Tank Search a custom Google search of over 670 think tank and research center websites
• MedNar :  deep web search engine of 60+ authoritative medical collections ( Article on using MedNar )
• OAIster:   digital resources from open archive collections worldwide 
• OpenGrey :  an archive of grey literature from Europe, downloadable as MySQL
• WorldWideScience.org :  global science gateway to international scientific databases
• WWW Virtual Library :  high quality subject guides
• OpenMD : search reference sites, government agencies, health organizations, and journals.
• BASE Search : for academic web resources

Some of the health sciences databases include types of grey literature. Here are a few:

• PubMed: some preprints
• Embase: conference proceedings and abstracts; preprints
• CINAHL: dissertations; articles from industry news and magazines
• PsycInfo: dissertations; conference proceedings
• Web of Science: conference proceedings and abstracts; articles from industry news and magazines
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• Grey Literature

What is Grey Literature?

Grey Literature is a field in library and Information science that deals with the production, distribution, and access to multiple document types produced on all levels of government, academia, business, and organization in electronic and print formats not controlled by commercial publishing i.e. where publishing is not the primary activity of the producing body.

Types of grey literature include theses and dissertations, conference proceedings, newsletters, reports, government documents, informal communications, translations, census data, research reports, technical reports, standards, patents, videos, clinical trials and practice guidelines, eprints, preprints, wiki articles, emails, blogs, listserv archives, and repository content.

For more recommendations of subject-specific grey literature resources beyond what is presented below, consult the USF Libraries Subject Guide most closely related to your topic.

Theses and Dissertations

• Dissertations & Theses @ University of South Florida - FCLA This link opens in a new window This database gives access to the dissertations and theses produced by students at USF.
• Networked Digital Library of Theses and Dissertations This link opens in a new window Features the Networked Digital Library of Theses and Dissertations (NDLTD), an initiative to improve graduate education, increase the sharing of knowledge, and help universities build their information infrastructure. NDLTD is a project team at Virginia Polytechnic Institute and State University in Blacksburg.
• ProQuest Dissertations and Theses, A&I This link opens in a new window This database is the world’s most comprehensive collection of dissertations and theses from around the world, spanning from 1743 to the present day. -- Simultaneous Users: Unlimited
• ProQuest Dissertations and Theses [PQDT] Global This link opens in a new window ProQuest Dissertations and Theses: Global (PQDTGlobal) is the world's most comprehensive collection of full-text dissertations and theses. As the official digital dissertations archive for the Library of Congress and as the database of record for graduate research, PQDTGlobal includes millions of searchable citations to dissertations and theses together with over a million full-text dissertations that are available for download in PDF format.
• WorldCat Dissertations and Theses [OCLC FirstSearch] This link opens in a new window Provides access to to over 5 million records of dissertations and theses available in OCLC member libraries catalogs in the WorldCat database. Many theses are available electronically, at no charge, directly from the publishing institution.

Conference Proceedings

Abstracts, poster presentations, and presented papers are considered grey literature because they may never be seen other than by those who attended the conference. however, they can be a good source of information about studies, particularly studies that never made it to publication..

• AIP Conference Proceedings This link opens in a new window AIP Conference Proceedings report findings presented at many of the most important scientific meetings around the world. Published proceedings are valuable as topical status reports providing quick access to information before it appears in the traditional journal literature. USF has perpetual access to the American Institute of Physics Journal Digital Archives.
• Conference Proceedings Citation Index [1990 Present] This link opens in a new window Conference Proceedings Citation Index, accessed via Web of Science Core Collection, helps researchers access the published literature from the most significant conferences, symposia, seminars, colloquia, workshops, and conventions worldwide. This resource offers a complete view of conference proceedings and their impact on global research, allowing researchers to use cited reference searching to track emerging ideas and new research beyond what is covered in the journal literature. -- USF's subscription includes: -- - Science - Social Sciences & Humanities -- Simultaneous Users: Unlimited
• PapersFirst [OCLC FirstSearch] This link opens in a new window Indexes over two million papers presented at conferences worldwide. Also covers congresses, expositions, workshops, symposiums, and other meetings. -- Simultaneous Users: Unlimited
• Proceedings [OCLC FirstSearch] This link opens in a new window Contains citations to proceedings of every congress, symposium, conference, exposition, workshop and meeting received at The British Library from October 1993 to the present. -- Simultaneous Users: Unlimited

Grey Literature Databases

• DOE Pages For access to journal articles and peer-reviewed accepted manuscripts resulting from DOE research funding, please visit the Department of Energy Public Access Gateway for Energy and ScienceBeta (DOE PAGESBeta), which is accessible and searchable at no charge to users.
• OpenGrey / SIGLE System for Information on Grey Literature in Europe (SIGLE) links to over 700,000 bibliographical references of grey literature produced in Europe and allows you to export records and locate the documents.
• Social Science Research Network This link opens in a new window The SSRN eLibrary consists of an abstract database containing abstracts of scholarly working papers and forthcoming papers and an electronic paper collection of downloadable full text documents in pdf format.
• National Criminal Justice Reference Service [NCJRS] Abstracts Database This link opens in a new window This database is published by the Office of Justice Programs, U.S. Department of Justice's National Criminal Justice Reference Service, an information clearinghouse for research, policy, and practice related to criminal and juvenile justice, and drug control. The NCJRS Abstracts Database contains summaries of U.S. and international publications, including federal, state, and local government reports, books, research reports, journal articles, audiovisual presentations, and unpublished research.
• PAIS Index This link opens in a new window This resource covers issues in the public debate through selective coverage of a wide variety of international sources including journal articles, books, government documents, statistical directories, grey literature, research reports, conference papers, web content, and more. PAIS International is the current file covering 1972 to present, and PAIS Archive includes the content from printed volumes published 1915-1976
• National Technical Reports Library (NTIS)   The NTIS serves as the largest central resource for government-funded scientific, technical, engineering, and business related information available today. For more than 60 years NTIS has assured businesses, universities, and the public timely access to approximately 3 million publications covering over 350 subject areas.
• ProQuest Congressional [Congressional Publications] This link opens in a new window Comprehensive online collection of primary source congressional publications and legislative research materials covering all topics, including government, current events, politics, economics, business, science and technology, international relations, social issues, finance, insurance, and medicine. Finding aid for congressional hearings, committee prints, committee reports and documents from 1970-present, and the daily Congressional Record from 1985-present. Compiled legislative histories from 1969-present.

Other Resources

• Grey Matters Grey Matters is an open access tool for national, international websites, clinical practice guideline producers, regulatory agencies, health economic resources, etc.
• OpenDOAR OpenDOAR is an authoritative directory of academic open access repositories.
• Grey Source GreySource provides examples of grey literature to the average net-user and in so doing profiles organizations responsible for its production and/or processing. GreySource identifies the hyperlink directly embedded in a resource, thus allowing immediate and virtual exposure to grey literature.
• Social Systems Evidence The types of syntheses in Social Systems Evidence include evidence briefs for policy, overviews of systematic reviews, systematic reviews, systematic reviews in progress (i.e. protocols for systematic reviews), and systematic reviews being planned (i.e. registered titles for systematic reviews). Social Systems Evidence also contains a continuously updated repository of economic evaluations in these same domains.
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Systematic Review and Evidence Synthesis

What is grey literature.

Grey (or gray) literature is literature produced by individuals or organizations outside of commercial and/or academic publishers. This can include information such as government reports, conference proceedings, graduate dissertations, unpublished clinical trials, and much more. The sources you select will be informed by your research question and field of study, but should likely include, at a minimum, theses and dissertations.

Why search grey literature?

The intent of an evidence synthesis is to synthesize all available evidence that is applicable to your research question. There is a strong bias in scientific publishing toward publishing studies that show some sort of significant effect. Meanwhile, many studies and trials that show no effect end up going unpublished. But knowing that an intervention had no effect is just as important as knowing that it did have an effect when it comes to making decisions for practice and policy-making. While not peer-reviewed, grey literature represents a valuable body of information that is critical to consider when synthesizing and evaluating all available evidence.

How do I search for grey literature?

Finding grey literature and searching it systematically is challenging. But there are a few approaches that you can take to add some structure to your search of this type of information:

Refer to grey literature sources used for related evidence syntheses . Refer to both published evidence syntheses and registered protocols.

Ask experts in the field for relevant grey literature sources . If you are an expert, include important grey literature sources, and ask colleagues for their recommendations.

Search databases that specialize in grey literature .

This Preprint Repository Syntax Table can help you to identify potential databases to search, and aid you in successfully constructing a search strategy

Search for theses and dissertations : There are a number of databases dedicated to theses and dissertations, which you can search using your search terms.

Search clinical trials : There may be clinical trials being conducted that are relevant to your research question, but that haven't been published yet or never were published.

Identify government agencies and international and non-governmental organizations that might publish technical papers and reports on your topic. Search their websites or any online libraries that they may provide . 

Search conference proceedings and newsletters : Identify professional organizations or conferences at which researchers might be presenting work related to your topic. Search those conference proceedings or newsletters on the organization's website or by contacting organizational boards for access to past proceedings that may not be online.

Contact known researchers in the field about whether there are any relevant ongoing or unpublished studies.

• Search professional and trade magazines. Professional magazines contain literature that is written by professionals in the field for other professionals in the field, but that may not be about research. Trade magazines contain advertisements and news very specific to a topic or industry.

Grey literature resources

Clinical trials.

Clinical trials may go unreported in the published literature. One useful method to identify unpublished clinical trials is to search clinical trials registries. The results may be available within the registries or you may need to contact the researchers associated with the trial for further information.

ClinicalTrials.gov

International Clinical Trials Registry Platform (WHO)

Clinical Trials Registers

Conference Proceedings

This list of conference proceedings is not comprehensive, but are ideas of where to search. We recommend that you search proceedings for the three most relevant conferences for your evidence synthesis.

OCLC PapersFirst OCLC PapersFirst is an OCLC index of papers presented at conferences worldwide.

Dissertations and Theses

Dissertations and theses are potentially rich sources of grey literature and are also usually considered grey literature themselves.

• Dissertations & Theses - How to find resources by format

Grey Literature Databases

WHO Library Database

The WHO library database includes governing documents, reports and technical documentation.

Preprint Repositories

Preprint repositories are free online archives that allow researchers to identify studies in rapidly developing fields and can be used to identify studies that have not gone through the more formalized and traditional peer review process​. Search and export functionality varies from site to site.

Preprints in Europe PMC

Includes bioRxiv, Research Square, Preprints.org, MedRxiv, ChemRxiv, PeerJ Preprints, F1000Res, SSRN, and others. Easy to export the basic citation to citation management software.

Free online archive of health sciences preprints (unpublished manuscripts) including original research articles, systematic reviews and meta-analyses, data articles, and articles describing methodological research/investigations and clinical research design protocols.

OSFPreprints: Preprint Archive Search

Aggregated search that covers preprint servers using the OSF infrastructure, e.g., AfricArXiv, AgriRxiv, Arabixiv, EcoEvoRxiv, EdArXiv, engRxiv, Frenxiv, IndiaRxiv, NutriXiv, PsyArXiv, SocArXiv and others, in addition to other preprint sources, e.g., arXiv, bioRxiv, cogPrints.

"SSRN is a platform for the dissemination of early-stage research. From its initial focus on the social sciences in 1994, SSRN has grown to become the most interdisciplinary service of its kind, representing disciplines across the full research spectrum, including the applied sciences, health sciences, humanities, life sciences, physical sciences, and social sciences."

Open access to over 1.9M e-prints in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance, statistics, electrical engineering and systems science, and economics.

bioRxiv: The Preprint Server for Biology

bioRxiv (bio-archive) is a free online archive and distribution service for unpublished preprints in the life sciences. Articles are not peer-reviewed, edited, or typeset before being posted online.

Preprint archive for engineering articles.

Research Preprints: Server List [Google Sheet]

Public Policy

​The World Bank now makes all of their publications openly available online.

WHO Institutional Repository for Information Sharing (IRIS)

Institutional WHO database of intergovernmental policy documents and technical reports. Can search by IRIS by region (Africa, Americas, Eastern Mediterranean, Europe, South-East Asia, Western Pacific).

Health Research Web

A wiki with descriptors of national health research systems, ethics review committees, local and regional policies and research priorities and more.

Other Resources

Grey Matters: A practical search tool for evidence-based medicine

This online manual provides a thorough list of sources for grey literature in medicine and a helpful checklist to help systematize your process.

Searching the grey literature: A handbook for searching reports, working papers, and other unpublished research

Searching the Grey Literature is for librarians and information professionals interested in learning more about grey literature. This book will aid with crafting a grey lit search successfully, from start to finish. Many types of librarians will find the content of this book useful, particularly those in health or social science.

Duke University Medical Center Guide to Resource for Searching the Grey Literature

Resources for trial registries, pharmacological studies, conference abstracts, government documents and more.

Gray Literature Resources for Agriculture Evidence Syntheses

This is a comprehensive list of agricultural grey literature sources, one of several evidence synthesis worksheets and tools provided to help in non-medical evidence synthesis development and implementation.

Searching for studies: A guide to information retrieval for Campbell Systematic Reviews

This document gives comprehensive guidance in searching for evidence syntheses, and offers a robust list of grey literature sources for social science disciplines.

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Research Process

• Brainstorming
• Explore Google This link opens in a new window
• Explore Web Resources
• Explore Background Information
• Explore Books
• Explore Scholarly Articles
• Narrowing a Topic
• Primary and Secondary Resources
• Academic, Popular & Trade Publications
• Scholarly and Peer-Reviewed Journals
• Grey Literature
• Clinical Trials
• Evidence Based Treatment
• Scholarly Research
• Database Research Log
• Search Limits
• Keyword Searching
• Boolean Operators
• Phrase Searching
• Truncation & Wildcard Symbols
• Proximity Searching
• Field Codes
• Subject Terms and Database Thesauri
• Reading a Scientific Article
• Website Evaluation
• Article Keywords and Subject Terms
• Cited References
• Citing Articles
• Related Results
• Search Within Publication
• Database Alerts & RSS Feeds
• Personal Database Accounts
• Persistent URLs
• Literature Gap and Future Research

Web of Knowledge

• Annual Reviews
• Systematic Reviews & Meta-Analyses
• Finding Seminal Works
• Exhausting the Literature
• Finding Dissertations
• Researching Theoretical Frameworks
• Research Methodology & Design
• Tests and Measurements
• Organizing Research & Citations This link opens in a new window
• Scholarly Publication
• Learn the Library This link opens in a new window

Additional Information

• Grey Literature Guides A directory of grey literature research guides, repositories, journals and conference proceedings, and training resources.

Grey Literature Defined

Grey literature is literature produced by government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers. A widely quoted definition of grey literature is "literature which is not readily available through normal book-selling channels, and therefore difficult to identify and obtain" ( Wood, 1982 ). Grey literature includes theses and dissertations, conference papers and proceedings, reports (such as white papers, working papers, internal documentation), government documents, technical notes and specifications, proposals, datasets/statistics, policies/procedures, patents, unpublished trial data, regulatory data, speeches, urban plans, test instruments, pre-prints, company information, social media, and more. A full list of  Document Types in Grey Literature is provided by GreyNet International.

It is crucial to note where the term “grey literature” derives from. Grey literature comes from the uncertainty of the status of this information. However, in cases where there may not be much information on a topic in peer-reviewed research, grey literature may prove a very valuable source of information and introduce alternate viewpoints. Additional benefits to using grey literature include:

• Grey literature can be published much more quickly since it does not have to be subjected to the lengthy peer-review process. Results of studies may appear in gray literature 12 to 18 months before being published via traditional channels.
• Online information from organizations may be updated more frequently than traditional published journals/books.
• Some grey literature may contain more depth—for example, a dissertation may include some raw data not published in a journal article that author goes on to write.
• Grey literature may provide a broader overview of an issue/topic, such as a white paper or fact sheet.
• Minimizes reporting or publication biases; grey literature is more likely to include negative results - e.g. clinical trials.

Locating Grey Literature

Grey literature may present a number of challenges for the researcher, making it difficult to identify and find. Consider the following when searching for grey literature:

• May not be widely disseminated
• May not be published online or not stable online (URL/website may change)
• Older documents may not be archived
• Format and citation information may be inconsistent
• Volume of material may be overwhelming and consuming
• May not have an international standard book number (ISBN) or an international standard serial number (ISSN)
• Typically not peer-reviewed and quality of evidence varies

Review the Evaluating Information Guide to help determine if a resource is appropriate for use in your research. The AACODS checklist is designed to enable evaluation and critical appraisal of grey literature.

The techniques below outline suggestions for locating select types of grey literature, as well as searching more broadly online. Please contact the Library with any questions.

Grey Literature Types

• Conference Proceedings
• Dissertations & Theses
• Government Documents
• Research Reports
• Social Media

Clinical trials are a form of grey literature  and can inform current research conducted by organizations, Federal agencies like the National Institutes of Health, academic institutions, and individual health care providers. These studies investigate the effectiveness of new treatments, interventions, drugs, procedures, and devices in order to improve health outcomes for a specific population. 

Several Library databases and online resources provide access to full-text clinical trials. See our Clinical Trials Guide for detailed instructions.

If you are unable to locate the full text for a particular clinical trial, you may submit an Interlibrary Loan request for the material.

A conference proceeding is the published record of a conference, congress, symposium, or other meeting sponsored by professional association or society. Proceedings typically include abstracts or reports of papers presented by the participants. When the entire  text of the papers presented is included, they are called transactions. For more information, see the FAQ: Are conference proceedings peer reviewed?

Conference papers and proceedings can be challenging to find because they may take several years to be published or may not be published at all. They can be published in various formats including books, abstracts, and journal articles; and, they may be deposited only in an author or institutional repository.

Some Library databases, like ProQuest , make it easier to search for these types of documents by allowing you to limit your search to Source type. Other databases that provide conference proceedings include IEEE Xplore, ACM Digital Library, LearnTechLib, CINAHL, and ERIC. These databases are available from the A-Z Databases page.

Previously published dissertations and theses can be a great source of inspiration for your own dissertation topic. You can access millions of full-text dissertations and theses from the Library. Go to the Library’s Dissertation Resources page to see a list of databases. You can specifically access dissertations from alumni via ProQuest Dissertations and Theses @ Northcentral University. Or you can explore the 3 million full-text dissertations available through ProQuest Dissertations and Theses Global.

For additional information and resources, see the Finding Dissertations Guide .

Government documents are an important primary source of information on a wide range of issues. Most government documents can be found through official government websites.

• Catalog of U.S. Government Publications Finding tool for federal publications that includes descriptive information for historical and current publications as well as direct links to the full document, when available.
• Data.gov The home of the U.S. Government's open data. Here you will find data, tools, and resources to conduct research, develop web and mobile applications, design data visualizations, and more.
• Electronic Code of Federal Regulations The codification of the general and permanent rules published in the Federal Register by the departments and agencies of the Federal Government produced by the Office of the Federal Register (OFR) and the Government Publishing Office.
• Federal Registrar Official journal of the federal government of the United States that contains government agency rules, proposed rules, and public notices.
• govinfo Provides free public access to official publications from all three branches of the Federal Government.
• HathiTrust A collection of U.S. Federal Documents as identified via the HathiTrust Federal Government Documents Registry.
• MetaLib Federated search engine that searches multiple U.S. Federal government databases, retrieving reports, articles, and citations while providing direct links to selected resources available online.
• Pueblo.GPO.gov Operated by the U.S. Government Publishing Office Pueblo Distribution Center (US GPO PDC) to support free federal publication distribution activities.
• U.S. Government Bookstore Allows users to search for and order Government information products currently available from the Information Dissemination area of the U.S. Government Publishing Office.
• U.S. Government Printing Office (GPO) Keeping America Informed as the official, digital, and secure source for producing, preserving, and distributing official Federal Government publications and information products for Congress, Federal agencies, and the American public.
• USA.gov USA.gov is the official U.S. portal to federal, state, local, tribal, and international government information and services.

A preprint is an author's working version of a research manuscript prior to publication. In most cases, they can be considered final drafts. Preprints may also be referred to as working papers or unpublished manuscripts. Preprints have not gone through the peer-review process, nor have they been improved upon by the publisher (e.g., formatting, copy-editing, technical enhancements). It is very important to critically evaluate preprint publications. Because the peer review process can take three to six months, preprints are a way to provide valuable research results and discussion ahead of publication. They are also a great way to locate information on emerging or rapidly changing research topics.

Preprints are published electronically and made publicly available on large databases or preprint repositories. The techniques below describe how to locate preprints in the Libray and online. Note when searching for preprints in Library databases, you do not want to select the peer-reviewed journal limiter.

EBSCO Business Source Complete

In Business Source Complete , select the Advanced Search screen. Scroll down to Publication Type and select Working Paper .

ProQuest Central

In ProQuest Central , select the Advanced Search screen. Scroll down to the Source Type limiter and select Working Papers .

PubMed Central

In PubMed Central, select the Advanced Search Builder . Enter the preprint[filter] command along with your topic keywords.

After conducting a search in Web of Knowledge (Web of Science), check the Early Access box under the Quick Filters on the left-hand side of the screen.

Preprint Repositories

• Advance: a SAGE preprints community Allows researchers within the fields of humanities and social sciences to post their work online and free of charge.
• arXiv Open access to more than a million e-prints in Physics, Mathematics, Computer Science, Quantitative Biology, Quantitative Finance and Statistics.
• Authorea Browse over 20,000 multi-disciplinary research preprints.
• bioRxiv Free online archive and distribution service for unpublished preprints in the life sciences.
• ChemRxiv Free submission, distribution, and archive service for unpublished preprints in chemistry and related areas.
• Figshare Repository where users can make all of their research outputs available in a citable, shareable and discoverable manner.
• medRxiv Free online archive and distribution server for complete but unpublished manuscripts (preprints) in the medical, clinical, and related health sciences.
• OSF Preprints (Open Science Framework) Free, open platform to support research and enable collaboration.
• PLOS Preprints Nonprofit, Open Access publisher empowering researchers to accelerate progress in science and medicine by leading a transformation in research communication.
• Preprints Preprints is a multidisciplinary preprint platform that accepts articles from all fields of science and technology.
• PsyArXiv A free preprint service for the psychological sciences.
• Research Square Research Square is a multidisciplinary preprint and author services platform.
• Rxivist Combines biology preprints from bioRxiv and medRxiv with data from Twitter to help researchers find the papers being discussed in their field.

Research reports contain the results of research projects, investigations, and surveys, and are usually published by the funder or the body undertaking the research. They can be found by searching the websites of subject associations and research organizations in addition to NU Library’s databases.

For example, you may limit your NavigatorSearch results to reports by using the limiters on the left-hand side of your results screen.

Social media and other Web 2.0 applications have become a valuable medium for for experts, governments and academics to publish new information and analysis outside of the traditional publishing arrangement. These sites may be useful as a way to disseminate information/results, follow experts and trending topics, and as a forum for exchange of ideas.

For a thorough overview of Web 2.0 grey literature sources, please see the Grey Literature: Grey 2.0 Guide from New York University.

Grey Literature Repositories

Grey literature repositories are curated collections of grey literature sources. You can use these collections to search or browse for resources for use in your research.

• BASE One of the world's most voluminous search engines especially for academic web resources. Note: Not exclusively grey literature.
• CORE World’s largest collection of open access research papers. Note: Not exclusively grey literature.
• Directory of Open Access Journals (DOAJ) Provides full-text, quality controlled scientific and scholarly, peer-reviewed journals in many subjects and languages. Note: Not exclusively grey literature.
• Grey Literature Publishers List The report is a publication produced by the The New York Academy of Medicine between 1999 - 2016, alerting readers to new grey literature publications in health services research and selected urban health topics.
• Grey Literature Report The report is a bimonthly publication of The New York Academy of Medicine alerting readers to new grey literature publications in health services research and selected urban health topics.
• GreySource Provides examples of grey literature and in so doing profiles organizations responsible for its production and/or processing.
• OAIster Searches across thousands of libraries and scholarly websites for open access content. Note: Not exclusively grey literature.
• OpenGrey Search portal for European grey literature covering Science, Technology, Biomedical Science, Economics, Social Science and the Humanities.
• Science.gov Gateway to U.S. Federal Science. Search over 60 databases and over 2,200 selected websites from 15 federal agencies, for research and development results.
• Google Custom Search
• Domain Limiter
• Document Type Limiter

There are a couple of Google custom searches that narrow your results to a specific type of organizational website. This may be helpful step when searching for grey literature. Enter your search terms into these pre-built basic search boxes to see your filtered results.

• NGO Search Google Custom Search Engine that searches across hundreds non-governmental organization (NGO) websites.
• IGO Search Google Custom Search Engine that searches across IGO websites--International governmental organizations made up of more than one national government. IGO examples include NATO (North Atlantic Treaty Organization) and the WHO (World Health Organization).

Google allows you to limit your search results to a particular domain (e.g., .edu, or .gov). This can be particularly helpful if you are looking for grey literature as you are more likely to find reliable content from organizations rather than commercial content.

Look for the "site or domain" box in Google's Advanced Search options and enter the domain you'd like to search, as shown below.

You can also do this by adding site:.edu (or .org, .gov, etc) to the end of your search terms in any Google search box. For example, to find articles about “ethical leadership” published on government websites, enter the terms "ethical leadership" site:.gov, as shown below.

Google also allows you to search for results with a specific file type (example: .pdf, .doc, .ppt, .xls). This is also helpful when looking for grey literature as government and organizational reports are more likely to be available as PDF or Word documents. Datasets may be provided as Excel files.

Look for the "file type" box in Google's Advanced Search options and select the file type you would like to search, as shown below.

You can also do this by adding filetype:pdf (or .doc, .ppt, .xls, etc.) to the end of your search terms in any Google search box. For example, to find PDF documents about “ethical leadership” enter the terms "ethical leadership" filetype:pdf, as shown below.

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Grey Literature

What is grey literature.

• Types of Grey Literature
• Conference Literature
• Government Documents
• Theses and Dissertations
• Using Search Engines
• Related Guides
• Getting Help

Grey literature is another form of literature sourced from nontraditional formats and publications. See below for additional definitions of grey literature provided by organizations and scholars affiliated with the field.

• Finding What Works in Healthcare
• International Conference on Grey Literature

GreyNet International

Cochrane Handbook

• The U.S. Interagency Gray Literature Working Group

"Grey literature includes trial registries (discussed below), conference abstracts, books, dissertations, monographs, and reports held by the Food and Drug Administration (FDA) and other government agencies, academics, business, and industry."

Institute of Medicine

"Grey literature is information produced outside of traditional publishing and distribution channels, and can include reports, policy literature, working papers, newsletters, government documents, speeches, white papers, urban plans, and so on."

The Third International Conference on Grey Literature in Luxembourg

"Grey Literature is a field in library and Information science that deals with the production, distribution, and access to multiple document types produced on all levels of government, academics, business, and organization in electronic and print formats not controlled by commercial publishing i.e. where publishing is not the primary activity of the producing body."

"The term ‘grey literature’ is often used to refer to reports published outside of traditional commercial publishing. Review authors should generally search sources such as dissertations and conference abstracts."

[Gray literature is] "foreign or domestic open source material that usually is available through specialized channels and may not enter normal channels or systems of publication, distribution, bibliographic control, or acquisition by booksellers or subscription agents."

From Farace & Schöpfel, 2010 , p. 1-2

Video Introduction to Grey Literature

Grey literature is very frequently referred to when conducting extensive literature reviews and evidence syntheses. See the video below, developed by the University of Northern Colorado, for a helpful background and definition on grey literature.

eBooks on Grey Literature in our Collection

Select the covers below to access eBooks available at Duquesne on the importance and use of grey literature. All are accessible via ProQuest Ebook Central.

• Next: Why Use Grey Literature? >>
• Last Updated: Feb 22, 2024 10:33 AM
• URL: https://guides.library.duq.edu/greylit

To read this content please select one of the options below:

Please note you do not have access to teaching notes, are electronic theses and dissertations (still) grey literature in the digital age a fair debate.

The Electronic Library

ISSN : 0264-0473

Article publication date: 3 April 2018

While distribution channels of theses and dissertations have changed significantly in the digital age, they are generally still considered grey literature. This paper aims to argue the applicability of the concept of grey to electronic theses and dissertations (ETDs).

Design/methodology/approach

The paper is presented as a debate between two contradictory opinions on the application of the grey literature concept to ETDs.

The paper provides a definition of grey literature and then discusses its application to electronic dissertations and theses. In particular, it assesses the aspects of acquisition, quality, access and preservation. Some arguments highlight the “grey nature” of ETDs, such as the limited access via institutional and other repositories. Other arguments (e.g. the development of ETD infrastructures and the quality of ETDs) question this grey approach to ETDs. The paper concludes that “greyness” remains a challenge for ETDs, a problem waiting for solution on the way to open science through the application of the FAIR (findability, accessibility, interoperability reusability) principles.

Research limitations implications

Library and information science (LIS) professionals and scientists should be careful about using the concept of grey literature. The debate will help academic librarians and LIS researchers to better understand the nature of grey literature and its coverage, here in the field of ETDs.

Originality/value

Some definitions from the print age may not be applicable to the digital age. The contradictory character of the debate helps clarify the similitudes and differences of grey literature and ETDs and highlights the challenge of ETDs, in particular, their accessibility and findability.

• Open access
• Academic publishing
• Grey literature
• Electronic theses and dissertations
• FAIR principles

Acknowledgements

The authors would like to acknowledge Gail McMillan from Virginia Tech for helpful comments and advice.

Schopfel, J. and Rasuli, B. (2018), "Are electronic theses and dissertations (still) grey literature in the digital age? A FAIR debate", The Electronic Library , Vol. 36 No. 2, pp. 208-219. https://doi.org/10.1108/EL-02-2017-0039

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Gray Literature: Dissertations & Theses

• What is Gray Literature?
• Conference Papers
• Data and Statistics
• Dissertations & Theses
• Government Documents and Law
• Think Tanks

Open Access Dissertations and Theses

• DART-Europe E-theses Portal Access to hundreds of thousands of Open Access research theses from European universities.
• Electronic Theses Online Service (EThOS) Search and access tens of thousands of theses from the UK.
• Social Science Research Network eLibrary Database Search Over 606,900 abstracts of scholarly working papers and forthcoming papers, and over 504,500 downloadable full text scholarly articles.
• Theses Canada Search and access thousands of electronic theses from Canadian Universities.
• EBSCO Open Dissertations
• OATD (Open Access Theses and Dissertations
• Penn State Open Educational Resources Penn State University
• Purdue University Open Access Dissertations
• UMass Amherst Open Access Dissertations
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Gray Literature: Beyond Peer Review

• Introduction
• Scientific literature
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• Oregon This link opens in a new window
• Non-governmental organizations (NGOs)
• Theses & dissertations
• Using Generative AI in Research

Where can I get more help?

Contact the OSU Libraries Information Desk

• Call us at 541-737-7293
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• Chat with a librarian
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• Visit the Valley Library information desk

Find OSU Theses & Dissertations

One of the best ways to get started with your literature review is to read other literature reviews from a completed thesis or dissertation written by someone from your department.

1. Find an OSU thesis or dissertation using ScholarsArchive@OSU

• Use a keyword search if you know the name of a past student or specific research topic. However, to get an overview of common trends in theses and dissertations in your department, use the search limiters on the left side of the page. 
• First (before entering any search terms), narrow by degree field . Click the "more" button, and then select the A-Z sort option to look through the list of degree names alphabetically. Choose the department or field name that matches your area of study.

• To find recent theses or dissertations, next refine your results on the left-hand side of the results page using the Date or  Commencement Year option. Expand the box, then enter your preferred date range. For example 2021-2023. Then click "limit."
• From this focused list of results, click on a thesis or dissertation title. 
• To  view the full text,  select the Download PDF link on the left side of the page.

2. Analyze the literature review you have selected.

• Use the table of contents to find the literature review. Sometimes there are multiple literature reviews in a single thesis or dissertation if your department uses the article format.
• How many sources are used to back up ideas?
• How old are the sources?
• Do sources come from multiple format types (e.g., journal articles, government websites, books, conference proceedings)?
• What citation style is used?
• How long is the literature review?
• How much depth does the author use to back up their ideas?
• How does the author transition from one idea to the next?

Other sources of theses & dissertations

These resources also index theses and dissertations.

ProQuest Dissertation Express : find citations here, then request it from OSU Libraries' Interlibrary Loan .

• PQDT Open Searches open access theses and dissertations from the ProQuest database. It is a subset of Dissertation Abstracts.
• Google Scholar  indexes many open access theses and dissertations from institutions and authors that have published them as open access. However, filtering to just dissertations and theses is not an option at this time.
• Check the OSU Libraries  database list to see if a database in your discipline indexes dissertations (many do) or ask your subject librarian for help selecting the best option.
• Networked Digital Library of Theses and Dissertations (NDLTD) Recommends several search engines for access to dissertations and theses.
• Search The Center for Research Libraries (CRL) catalog to view citations of over 800,000 dissertations from countries outside the US and Canada. Where available, request full-text from the CRL through Interlibrary Loan .
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Systematic Reviews: Searching the Gray Literature

• What Type of Review is Right for You?
• What is in a Systematic Review
• Finding and Appraising Systematic Reviews
• Formulating Your Research Question
• Inclusion and Exclusion Criteria
• Creating a Protocol
• Results and PRISMA Flow Diagram
• Searching the Published Literature
• Searching the Gray Literature
• Methodology and Documentation
• Managing the Process
• Scoping Reviews

How to Manage the Grey Literature Search

• Identify and record the sources you will search. The sources you search will be informed by your research question and where you expect to find information related to your question.
• Document  where you are searching and your search strategies, including document resource name, URL, search terms, and date searched.
• Collect  citation information as you go.
• Adhere  to your established inclusion and exclusion criteria when selecting sources.

Google Scholar

Google Scholar has it's place in research. That being said, GS is not great for doing a systematic review. The filters are not good, you can't build an advance search, and the Google algorithm is unknown. It can be used for gray literature searching through. Do a simplified search in GS and use the first 300 results or the first few pages of results. 

The gray literature: What is it and how do I search it?

What is gray literature? 

Gray literature is defined by the  Cochrane Handbook for Systematic Reviews of Interventions  as "...literature that is not formally published in sources such as books or journal articles." This can include information such as government reports, conference proceedings, graduate dissertations, unpublished clinical trials, and much more. The sources you select will be informed by your research question and field of study, but should likely include, at a minimum, theses and dissertations.

Why search the gray literature if it hasn't been peer-reviewed? 

The intent of an evidence synthesis is to synthesize  all available evidence  that is applicable to your research question.

There is a strong bias in scientific publishing toward publishing studies that show some sort of significant effect.  Meanwhile, many studies and trials that show no effect end up going unpublished.  But knowing that an intervention had no effect is just as important as knowing that it did have an effect when it comes to making decisions for practice and policy-making.  Thus, the gray literature can be critical.

How do I search the gray literature if it's unpublished and not in the scholarly databases?  

Its true--finding gray literature and searching it systematically is challenging.  But there are a few approaches that you can take to add some structure to your search of this type of information:

• Identify and record  the sources you will search, including some indication of search terms used if appropriate.  The sources you search will be informed by your research question and where you expect to find information related to your question.
• Try searching  databases that specialize in gray literature  like  OpenGrey .  See the box below for more information.
• Conference proceedings :  Identify professional organizations that have conferences at which researchers might be presenting work related to your topic.  Search those conference proceedings on the organization's website or by contacting organizational boards for access to past proceedings that may not be online.
• Theses and dissertations:   There are a number of databases dedicated to theses and dissertations, which you can search using your search terms.  See the box below for links to these resources. 
• Identify government agencies, and international and non-governmental organizations , that might publish technical papers and reports on your topic.  Search their websites or any online libraries that they may provide.  For example, the  WHO  has a number of searchable online collections and the  World Bank  now makes all of their publications openly available online.
• Contact known researchers  in the field to determine if there are any ongoing or unpublished studies that s/he may be aware of.
• Grey Literature Reporter The Grey Literature Reporter is a Google Chrome extension that you train on the search results of the current website that you are on. It will then record the results – as JSON, CSV and potentially RIS – as well as the URL of the site and the search string used. With this extension you can easily start your search, click on the extension and tell it where the 1st result item is, tag all the relevant data in that result and automatically scrape the rest of the results and pages. Even if the markup changes for the site the next time you go to it will not matter as the extension is shown each time what elements on the page you’re interested in.

Grey Literature Sources

• Guidance Documents for Gray Literature Searching
• Gray Literature Databases
• Thesis and Dissertations
• Clinical Trials
• Public Policy
• Government Documents
• Other Resources
• Grey Matters: a practical tool for searching health-related grey literature This online manual provides a thorough list of sources for gray literature in medicine and a helpful checklist to help systematize your process.
• Simon Fraser University Searching Grey Literature Guide
• Duke University Medical Center Guide to Resource for Searching the Gray Literature A more thorough guide to gray literature, including resources for trial registries, pharmacological studies, conference abstracts, government document and more.
• Gray Literature Resources for Agriculture Evidence Syntheses
• OpenGrey: System for Information on Grey Literature in Europe The System for Information on Grey Literature in Europe, is an open access database to 700.000 bibliographical references of gray literature produced in Europe and allows you to export records and locate the documents in many research disciplines.
• NY Academy of Medicine Grey Literature Report This report is a bimonthly publication of The New York Academy of Medicine (NYAM) alerting readers to new gray literature publications in health services research and selected public health topics. The database platform is keyword searchable and serves as an archive for the cataloged reports.
• WHO Library Database The WHO library database includes governing documents, reports and technical documentation.
• MedNar MedNar searches across more than 60 medical research sources, including commercial databases, medical societies, NIH resources, and other government resources.
• Center for Research Libraries A resource for institutions outside of the U.S. and Canada.
• Dissertations & Theses @ Louisiana State University This link opens in a new window This database gives access to the dissertations and theses produced by students at your institution.
• EThOS Electronic Theses Online Service contains doctoral theses from candidates in the UK.
• LSU Scholarly Repository This link opens in a new window LSU Scholarly Repository provides access to research, publications, data, and records produced by LSU faculty, students, and units. It includes but is not limited to online versions of various theses and dissertations from LSU graduate students. To learn more about contributing, contact [email protected].
• Networked Digital Library of Theses and Dissertations (NDLT) Free international resource for theses and dissertations.
• Open Access Theses and Dissertations (OATD) OATD.org aims to be the best possible resource for finding open access graduate theses and dissertations published around the world. Metadata (information about the theses) comes from over 1100 colleges, universities, and research institutions. OATD currently indexes 4,444,117 theses and dissertations.
• ProQuest Dissertations & Theses A&I This link opens in a new window Contains citations to 1.2 million dissertations and masters theses. Coverage begins in 1861, with abstracts available since 1980, and thesis abstracts since 1988.
• Australia New Zealand Clinical Trials Registry Online register of clinical trials being undertaken in Australia, New Zealand and elsewhere. The ANZCTR includes trials from the full spectrum of therapeutic areas of pharmaceuticals, surgical procedures, preventive measures, lifestyle, devices, treatment and rehabilitation strategies and complementary therapies.
• ClinicalTrials.gov The US registry for clinical trials. Includes new, ongoing and completed human clinical trials both in the US and in countries around the world.
• Cochrane CENTRAL Register A highly concentrated source of reports of randomised and quasi-randomised controlled trials. The majority of CENTRAL records are taken from bibliographic databases (mainly MEDLINE and Embase), but records are also derived from other published and unpublished sources.
• EU Clinical Trials Register The European Union Clinical Trials Register allows you to search for protocol and results information on interventional clinical trials that are conducted in the European Union (EU) and the European Economic Area (EEA) and clinical trials conducted outside the EU / EEA that are linked to European paediatric-medicine development.
• WHO International Clinical Trials Registry Platform (ICTRP) This Clinical Trials Search Portal provides access to a central database containing the trial registration data sets provided by numerous international registries. It also provides links to the full original records.
• Wikipedia clinical trial registries list This Wikipedia entry contains a list of links to individual clinical trial registries by country.
• Health Research Web A wiki with descriptors of national health research systems, ethics review committees, local and regional policies and research priorities and more.
• Pew Research Center Pew Research Center is a nonpartisan fact tank that informs the public about the issues, attitudes and trends shaping America and the world. It conducts public opinion polling, demographic research, media content analysis and other empirical social science research.
• Policy Agendas Project The Policy Agendas Project collects and organizes data from various archived sources to trace changes in the national policy agenda and public policy outcomes since the Second World War, including congressional hearing, roll call votes, executive orders, supreme court cases etc.
• Policy Archive Online archive of public policy research. Access open to all Internet users.
• Think Tanks (Harvard Kennedy School Library) Harvard's Kennedy School of Government Library compiles a list of links to public policy think tanks. Access open to all Internet users.
• WHO Institutional Repository for Information Sharing (IRIS) Institutional WHO database of intergovernmental policy documents and technical reports. Can search by IRIS by region (Africa, Americas, Eastern Mediterranean, Europe, South-East Asia, Western Pacific).
• World Bank ​The World Bank now makes all of their publications openly available online.
• Catalog of U.S. Government Publications (GPO Monthly catalog) Provides citations to U.S. federal government publications. Contains references to books, reports, studies, serials, maps and other publications. Topics covered include finance, business, demographics, foreign relations, public health and social issues.
• Congress.gov Offers full-text bills and bill tracking back to the 93rd Congress (1973) and also Congressional committee information.
• Congressional Research Service Reports This collection provides the public with access to research products produced by the Congressional Research Service (CRS) for the United States Congress. By law, CRS works exclusively for Congress, providing timely, objective, and authoritative research and analysis to committees and Members of both the House and Senate, regardless of political party affiliation.
• CQ Researcher Plus Archive This link opens in a new window A database of in-depth, authoritative reports on a full range of political and social-policy issues extending back to 1923. Each report is footnoted and includes an overview, background section, chronology, bibliography and debate-style pro-con feature, plus tools to study the evolution of the topic over time.
• CQ Weekly This link opens in a new window A weekly news magazine featuring in-depth reporting on public policy, politics, congressional legislation, and elections extending back to 1983, including: a complete wrap-up of news on Congress, the status of bills in play, behind-the-scenes maneuvering, committee and floor activity, debates, and all roll-call votes.
• GovInfo.Gov Provides online access to the U.S. Government Printing Office. This service was mandated by Public Law 103-40 (June 8, 1993), "The Government Printing Office Electronic Information Access Enhancement Act of 1993," to make the Federal Register and other Congressional information available to the public.
• Hayley Johnson Head of Government Documents & Microforms
• ProQuest Congressional Publications This link opens in a new window Description: Provides access to Committee Prints & Miscellaneous Publications, Congressional Research Service (CRS) Reports, and Congressional Hearings (1824-2003)

Googling the Greys: Tips for Searching Beyond Health Databases and Turning Information into Insights

A thorough grey literature search should involve a general sweep of the web by using different search engines. Google is an important search engine but other search engines, such as Yahoo and Bing, could also be useful.

While Google is a powerful tool for searching for grey literature it should not be used exclusively - other sources should also be searched in order to find grey literature. 

1) Restrict content to .org or .gov sites

Type in your topic and then either "site:.org" OR "site:.gov"

2) Restrict content to file type

Type in your topic and then "filetype:pdf" OR "filetype:doc"

3) Use Google Australia, Google UK, etc.

4) Use the Duck Duck Go search engine which does not record location or user searches

5) Use Link Klipper (Chrome extension) to pull results into a Microsoft Excel spreadsheet. You can also use the Grey Literature Search Log form linked below to keep track of your searches:

• Grey Lit Search Log
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• Last Updated: Mar 5, 2024 3:43 PM
• URL: https://guides.lib.lsu.edu/Systematic_Reviews

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