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Systematic Reviews and Evidence Syntheses: Grey literature

How to do and find systematic reviews.

Searching for grey literature and on-going research

​Grey literature is generally considered to be material published or made available by organisations or individuals, not through commercial publishers. This can include: clinical study reports, conference abstracts, government documents, organisational reports, personal communication, pre-prints, regulatory documents, study registrations, social media posts and theses.

Searching for grey literature can be problematic, as it isn't collected, organised or stored in a consistent way. You will need to be flexible in your approach, depending on the type of grey literature you need – this will differ from review to review.

Here are a few suggestions on where to look. Please also contact your outreach librarian or subject librarian for advice related to your review.

General resources

Conference abstracts & proceedings

Dissertations & theses



Trials registers

Reporting your grey literature

Reporting your grey literature search is not as straightforward as reporting a search on a bibliographic database. You should aim to record the following information:

  • Name of web-site or resource used
  • URL (if appropriate)
  • Date of search
  • Keywords  used for searching or details of how you browsed

Further reading