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What is grey literature?

'Grey literature stands for manifold document types produced on all levels of government, academia, business and industry in print and electronic formats that are protected by intellectual property rights, of sufficient quality to be collected and preserved by library holdings or institutional repositories, but not controlled by commercial publishers i.e., where publishing is not the primary activity of the producing body.'
(Schöpfel, 2010)

Grey literature includes: 

  • reports (government and non-government)
  • organisation websites or publications from organisations - including brochures, leaflets, fact sheets & bulletins
  • policy documents, working papers, technical reports
  • patents
  • theses & dissertations
  • conference proceedings
  • clinical trials
  • surveys, interviews & personal communications
  • census & other data & statistics sources
  • respositories & digital libraries eg e-print or pre-prints of articles, theses, research reports
  • blogs, podcasts & video
  • social media networks (Twitter, wikis etc).

To evaluate grey literature use the AACODS checklist.

 Sources for grey literature:

See also:

Systematic reviews and grey literature:

Mahood Q, Eerd DV, Irvin E. Searching for grey literature for systematic reviews: challenges and benefits. Research Synthesis Methods. 2014;5(3):221-34.

You might prefer to watch a video from the Harvey Cushing/John Hay Whitney Medlical Library, Yale University on grey literature

Schöpfel, J. (2010. Towards a Prague definition of grey literature. Paper presented at the Twelfth International Conference on Grey Literature: Transparency in Grey Literature. Grey Tech Approaches to High Tech Issues, Prague, 6-7 December 2010. Retrieved from

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