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Grey Literature: Home

What is grey literature? How do I find Grey Literature?

Grey Lit Tiers

1st - Significant retrievability, credibility

  • Book, book chapters, government reports...

2nd - Moderate retrievability, credibility

  • Annual reports, news articles, company publications

3rd - Low retrievability, credibility 

  • Blogs, emails, tweets, letters

(Adams R.J., 2016)

Grey Literature Use

Grey Literature is commonly used in conducting Systematic Reviews, Literature Reviews and Meta-Analyses. Most grey literature is used in practice, both clinically and professionally. 

Grey Literature Definition

Grey Literature Definition

According the the National Library of Medicine, Grey (gray) literature is "that which is produced on all levels of government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers," -- Luxembourg Convention.

This category includes reports, memoranda, conference proceedings, standards, technical documentation, and government documents.

Some refer to grey literature as 'fugitive literature', unpublished materials that can be difficult to find, and that is why it is called Grey literature.

There are over 150 different document types in Grey Literature. A list of those types can be found here:


Types of Grey Literature

For you visual learners, here is a Venn Diagram with various forms of grey literature, and shows how wide the field of grey literature is and how much of it plays a strong part in clinical decisions. 

Image obtained from: Rose Relevo Slide Presentation from the AHRQ 2011 Annual Conference 9/20/11

Medical Research Librarian

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Alysha Sapp
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