Grey literature or types of non-formally published substantive literature
What is Gray Literature?
Gray (or grey) literature is literature produced by individuals or organizations outside of commercial and/or academic publishers. This type of non-formally published substantive information (often not formally peer-reviewed; especially important in all kinds of sciences) can include information such:
- theses and dissertations
- technical reports
- working papers
- government reports
- evaluation and think tank reports and resources
- conference proceedings, papers and posters
- publications from NGOs, INGOs, think tanks and policy institutes
- unpublished clinical trials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?
Most of gray literature is considered less prestigious, reliable, and "official" than publication in a peer-reviewed journal. But they are still fully legitimate avenues of publication. Often they are used to publicize early findings, before a study is entirely complete. Or, in the case of theses, they are published as a condition of receiving an advanced degree. Government technical reports are issued either by agencies that do scientific research themselves or else by a lab that has received government funding. Increasingly, such labs may be required to publish technical reports as a condition of receiving such funding. Gray literature may be cited like any other paper although with the caveat mentioned before that it is considered less "official" and reliable than peer-reviewed scientific papers.
When doing evidence synthesiis, it's important because the intent 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 Meanwhile, many studies and trials that show no effect end up going unpublished.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 While not peer-reviewed, gray literature represents a valuable body of information that is critical to consider when synthesizing and evaluating all available evidence.
How to Manage the Grey Literature Search (particularly for evidence synthesis)
- 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.
What are technical reports? Technical reports present facts and conclusions about technological designs and projects. Typically, a technical report includes research about concepts as well as graphical depictions of designs and data. A technical report also follows a strict organization. Thus, when engineers read it, they can quickly locate the information they need.1
A technical report is a form of grey literature: Reports or documents produced by academia, government, industry or nonprofit organizations describing their work, proposals and/or the challenges they face. Grey literature is copyrighted like most other published work, but it usually is not distributed by commercial publishers the way a book or periodical would be but rather by the authoring organization itself. The organization that publishes the report is usually considered the 'author' (even if named individuals are credited within the report).
Some sources of technical reports:
- Sample technical reports on renewable energyProf. Ahlers has provided these specific examples of technical reports produced by corporations and organizations regarding proposals for renewable energy projects. Take a look.
- OSTI SciTech ConnectThe Department of Energy (DOE) Office of Scientific and Technical Information (OSTI) maintain SciTech Connect, a portal to free, publicly available Dept. of Energy research and development results.
- NTRS - The NASA Technical Reports ServerCollected from U.S. and international sources, NTRS is a collection of information that includes over 4 million bibliographic records and a growing number of full-text documents.
Preprints and Working Papers
Working papers are preliminary works, released to share ideas or invite discussion and feedback, often prior to the submission of a paper to a peer-reviewed journal or conference. Economists have traditionally relied on working papers as a method for the timely and informal communication of recent research findings.
- IDEAS (Hosted by RePEc)"IDEAS is the largest bibliographic database dedicated to Economics and available freely on the Internet. Based on RePEc, it indexes over 3,000,000 items of research, including over 2,700,000 that can be downloaded in full text."
- NBER Working PapersNBER researchers initially report their findings in these scientific papers aimed at other professional economists. Nearly 700 NBER Working Papers are published each year, and many subsequently appear in scholarly journals.
- LawArXivLawArXiv is a free, open access repository for legal scholarship, maintained and owned by legal scholars and law librarians for the benefit of the legal community.
How to Search the Grey Literature (particularly for evidence synthesis)
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:
- Search databases that specialize in gray literature: See the box below 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 box below 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 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. See the box below 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 box below 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.
Other Useful Guides
Technical reports (NASA, DOE, etc.)
by Jill Powell Last Updated Jan 30, 2023 466 views this year
by Jill Powell Last Updated Jan 30, 2023 680 views this year
Dissertations and Theses: A Finding Guide
by Michael Engle Last Updated May 12, 2023 2021 views this year
Dissertations & Theses in Engineering
by Jill Powell Last Updated May 4, 2022 224 views this year
Standards & Building Codes
by Jill Powell Last Updated Mar 8, 2023 341 views this year
Grey Literature Sources
- OpenGrey: System for Information on Grey Literature in EuropeThe 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. OpenGrey covers Science, Technology, Biomedical Science, Economics, Social Science and Humanities topics.
- NY Academy of Medicine Grey Literature ReportThis 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 DatabaseThe WHO library database includes governing documents, reports and technical documentation.
- MedNarMedNar searches across more than 60 medical research sources, including commercial databases, medical societies, NIH resources, and other government resources.
- ProQuest Dissertations and ThesesWith more than 2 million entries, PQD&T is the single central, authoritative resource for information about doctoral dissertations and master's theses.
- Networked Digital Library of Theses and Dissertations (NDLT)Free international resource for theses and dissertations.
- Center for Research LibrariesA resource for institutions outside of the U.S. and Canada.
- OCLC WorldCat Dissertations and Theses"This database provides fast and convenient access to the dissertations and theses available in OCLC member libraries. Many theses are available electronically, at no charge, directly from the publishing institution."
- Guide to Theses and Dissertations ResourcesThis guide provides information on finding and accessing both Cornell and non-Cornell theses and dissertations, including many resources for non-US literature.
- EThOSElectronic Theses Online Service contains doctoral theses from candidates in the UK.
- ClinicalTrials.govThe 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 TrialsA 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 RegisterThe 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.
- Australia New Zealand Clinical Trials RegistryOnline 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.
- WHO International Clinical Trials Registry PlatformICTRP 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 ListThis Wikipedia entry contains a list of links to individual clinical trial registries by country.
- World BankThe 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 WebA wiki with descriptors of national health research systems, ethics review committees, local and regional policies and research priorities and more.
- OCLC PapersFirstOCLC PapersFirst is an OCLC index of papers presented at conferences worldwide.
- BIOSIS PreviewsA subcollection of Web of Science, BIOSIS Previews searches across journals, meetings, patents, and books in the life sciences and biomedical fields.
- Grey Matters: A practical search tool for evidence-based medicineThis 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 InsightsThis 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 Grey LiteratureResources for trial registries, pharmacological studies, conference abstracts, government document and more.
Grey Literature Resources for International Agriculture & Development
Not all websites are created equal! Major nongovernmental organizations and various scholarly associations can be rich and authoritative websites, especially for the kind of grey literature not published in mainstream scholarly journals (including white papers, evaluation reports, training materials, and the like). Below are a few useful places to start.
- Cornell International Institute for Food, Agriculture, and Development (CIIFAD)This rich site also has a good section of other international resources at Cornell.
- International Initiative for Impact Evaluation"3ie funds impact evaluations and systematic reviews that generate high quality evidence on what works in development and why. Evidence on development effectiveness can inform policy and improve the lives of poor people."