What is Grey Literature?

A Definition of "Grey Literature":

"information produced on all levels of government, academics, business and industry in electronic and print formats not controlled by commercial publishing, where publishing is not the primary activity of the producing body"
-ICGL Luxembourg definition, 1997. Expanded in New York, 2004 http://www.greylit.org/about 

Examples of Grey Literature Types

Some examples of grey literature include:

  • Government publications
  • White papers produced by private consultancies
  • Academic dissertations and theses
  • Research reports published by not-for-profits, think tanks, or trade organizations
  • Unpublished clinical trials
  • Blogs

Please see Document Types in Grey Literature for a full list of grey literature document types, managed by GreyNet

Guides to Grey Literature

Many academic libraries and nonprofit organizations have freely available, great reference resources that provide a good  overview of grey literature. Below is an annotated list of library web pages on grey literature indicating their strengths.


Grey Literature Library Page, University of New South Wales, Sydney: This excellent site provides a good introductory overview of grey literature.  The last link on the page is a link to the library’s subject guide for Public Health & Community Medicine, which contains very useful resources for health grey literature.
Grey Literature – For Researchers, Southern Cross University: This concise guide is aimed at researchers and has a useful section on databases that index grey literature.


Grey Literature Overview, Knowledge Resource Service, Alberta Health Services: This page gives an excellent, concise overview of grey literature from a guide focused on health care information.
Grey Literature LibGuide, Bow Valley College:
 This guide has an excellent section on how using grey literature reduce/avoid publication bias.
About Grey Literature, Sheridan College: This LibGuide gives an excellent overview of what grey literature is and why it is important, and the “citing grey literature” tab gives guidance on how to cite grey literature sources in six popular citation styles.
Specialized Resources, Gambling Research Exchange (GREO): This page introduces grey literature in the context of GREO’s Evidence Centre database, which has an extensive collection of grey literature on gambling harms included problem gambling. The page describes the value and challenges with using grey literature, and the inclusion criteria GREO uses for grey literature collection development.
Grey Literature for Health Information Science and Health Sciences, University of Victoria: This LibGuide introduces grey literature with a unique perspective of grey literature as “Between the extremes of black and white”.

United Kingdom

Grey Literature Resource Guide, Lancaster University: This resource guide gives a succinct overview including a definition, types, search tips and the AACODS grey literature evaluation framework.

United States

Grey Literature LibGuide, Shimberg Health Sciences Library, University of South Florida: This guide gives a brief overview of the different types of grey literature and how to search them. The “Global Indices” section is helpful particularly for research topics with an international scope (e.g. COVID-19).
Grey Literature Research Guide, University of Michigan: This thorough and well-organized research guide has an exceptional section on strategies for finding grey literature, and a helpful social media citation guide under “Other Resources
Grey Literature, Duke University LibGuide: This page emphasizes the importance of grey literature in addressing publication bias in systematic reviews.
Grey Literature Resource Guide, Norris Medical Library, University of Southern California: This site contains a wealth of information on the role of grey literature within the health sciences. It also provides a selection of grey literature databases, a number of which are open access.
Survival Guide for Scholarship, Dissertations, Theses, and Scholarly Projects: Introduction to Grey Literature, Massachusetts General Hospital: From a “survival guide” targeted at graduate students, this site offers a user-friends, plain-language introduction to grey literature and how to use it in one’s scholarship