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Public Health Resources

What is Grey Literature

Grey literature refers to both published and unpublished research material that is not available commercially. In general, grey literature publications are non-conventional and sometimes ephemeral publications that are not indexed in databases such as PubMed and Embase.

Grey literature includes:

  • Clinical trials
  • Dissertations and theses
  • Conference proceedings
  • Government reports and documents
  • Maps
  • Newsletters
  • Pamphlets
  • Reports
  • Social media: Twitter, Facebook, LinkedIn, etc.
  • Statistics and data
  • Technical specifications and standards
  • Technical and commercial documentation
Why search grey literature:
  • Including unpublished results reduces publication bias, which includes the phenomenon that studies reporting a positive result are more likely to be published than those finding a negative result.
  • Incorporating unpublished trial data can change statistical results.
  • Global literature should be included.
  • Grey literature is often more current.
  • Current IOM systematic review standards call for grey literature inclusion.

Referencing and Citing Grey Literature

Consider using a citation management program to organize your search results.

  • Data to include in your references:
    • Author or (organizational author)
    • Year of publication
    • Title
    • Publisher information (for printed documents)
    • Retrieved from and URL (for online material)

Read More about Grey Literature