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Health Library Guide to finding Grey Literature

Discover resources and strategies for finding Grey Literature

All about Grey Literature


What is Grey Literature

Grey literature comprises "documents produced on all levels of government, academia, business and industry in print and electronic formats" ... but which is "not controlled by commercial publishers i.e., where publishing is not the primary activity of the producing body.”    

Schöpfel, J. (2010) 'Towards a Prague Definition of Grey Literature." Transparency in Grey Literature. Grey Tech Approaches to High Tech Issues:12th International Conference on Grey Literature. Prague, 6-7 December 2010,  pp.11-26. 

When doing health science/public health research, looking for grey literature can help you find

  • recent statistics, data & most recent clinical results
  •  more detailed reports than journals can publish.

It can help you avoid missing important information due to

  • publication lag caused by time delays between presentation of results in conference proceedings & their publication in peer reviewed journals  
  • positive result bias which is the tendency of journal publishers to prefer publishing only positive study results over negative ones.  

A Grey Literature search may be a requirement of an exhaustive evidence-based research project such as

  • A literature review
  • A scoping review

 If your research will benefit from looking beyond traditional, commercially  published journals, or if the type of study you are doing requires you to find Grey Literature, ask yourself the following:

What kind of research document would contain the information I need?

  • Clinical trials?
  • Conference proceedings, papers or posters?
  • Dissertations or theses?
  • Government publications?
  • Professional guidelines?

Who would publish this kind of information?

  • Government bodies?
  • Professional organizations/societies?
  • Advocacy groups?
  • Academic institutions?
  • Industry?

Much of the information created by these different entities is searchable & freely available on the internet.


  • Conference proceedings/ conference papers/ posters
  • Clinical trials
  • Dissertations/Theses
  • Drug regulatory information
  • Fact Sheets
  • Guidelines
  • Government documents
  • Policies & procedures
  • Preprints
  • Program evaluation studies
  • Working papers... and many more

Start your search by finding webpages of health research agencies that may produce relevant information.

New York Academy of Medicine's Grey Literature Publisher List :This resource provides a list of agencies with links to the reports that they create.
Grey Matters: a practical tool for evidence-based searching:  CADTH (Canadian Agency for Drugs and Technologies in Health) provides a comprehensive list of Canadian and International Health technology agency websites.
GreyNet International seeks to identify & distribute information on and about grey literature in networked environments.
OpenDOAR is a global Directory of Open Access Repositories. You can search&browse through thousands of registered repositories based on a range of features, such as location, software or type of material held.


Use Google Search syntax to find documents from specific places & in specific formats

Common Institutions/Organizations Specific Countries Specific  document formats
United States academic .edu Cyprus .cy Adobe acrobat doc .pdf
UK academic

European Union   .eu

word document .doc

 Non- commercial .org

Greece  .gr power point  .ppt
Non-governmental .ngo or .ong United Excel spreadsheet  .xls
US government ⇒ .gov United States ⇒  .us
See also: See also:  

  • Use these basic web search tricks to isolate research documents from other types of web content
    • Example:  enter your topic: alcohol abuse followed by  to zero in on information from relevant organizations
    •  Example: enter your topic: impetigo followed by filetype:pdf to zero in on specific document type
  • Consider using a web browser such as Duck Duck Go to avoid search engine optimization interfering with how your results display or having your results influenced  or limited by searches you have done previously.
  • Consider using different country versions of Google such as  .uk.  .au  .cy .gr  etc.
  • Always go beyond the first page of your results. Scan at least the first 100 hits.

Use advanced Google commands directly in the search box 

Google search syntax

allintext : search for documents with specific words in the text allinurl : find search terms in url inauthor :  find books written by specific author intitle : find your term in the title & document link :  find sites that link to a desired URL location : find results from a location (Google News only)
related : find web pages that are similar to a URL (helps find organizations you are not familiar with) site:country code : search for results from a specific country source :  find results from a specific source ? or * : internal & end of word wildcards :  exclude a search term from your results “ ” :  search by phrase all words together