Skip to Main Content

Grey Literature

What is Grey Literature?

Image displaying possible grey literature sources, for example, websites and policy documents

Possible Grey Literature sources 

Grey Literature comprises material available directly from various agencies or institutions, often via their individual websites. It includes technical reports, official publications, policy documents, conference papers, dissertations, and working papers, mainly produced by academic, government, and professional organisations. Examples include documents of the HSE in Ireland, the NHS in the UK, and global entities like the World Health OrganizationNotably, these documents are typically not indexed in journal databases like Medline and Embase. 

Grey Literature Tips

Searching Platforms:

  • You may of course use platforms like Google or Google Scholar to get started, however there are other options (see Search Engines below). The results returned by Google Scholar will not necessarily be only grey literature as they search across many academic papers as well.

Search Approaches:

  • Take references from reputable studies and search for them. 
  • Systematically search the websites of relevant agencies. You will have to identify what agencies are relevant to your needs. 
  • Agencies may include national or regional bodies, charities, patient groups, advocacy organizations, and professional bodies.

Search Process Tips:

  • Multiple basic searches or page browsing may be necessary.
  • Keep in mind, that some organizations may have limited search capabilities.
  • This guide compiles recommended grey literature sources, categorized into Irish and International Resources. Review the list, but remember it is not exhaustive.

Search Engines

Search Engines

  • BASE (Bielefeld Academic Search Engine) - BASE is one of the world's most voluminous search engines for academic open access web resources and contains European research resources indexed by Bielefeld University. This is a large powerful search engine and its ‘Advanced Search ’ functionality enable results to be filtered by document type (‘report’ or ‘manuscript’ or ‘review’ or ‘thesis’).    
  • MedNar - Mednar is a health sciences oriented deep web search engine produced by the University of Southern California. MedNar searches openly available medical and health resources that generally cannot be found through a typical Google search; results include grey literature.
  • TRIP - an established database indexing many non-standard types of content. 

Specific Guidance on Grey Literature

Grey Literature Guidance

  • GreySource - provides links to self-described sources of grey literature. Only web-based resources that explicitly refer to the term grey literature (or its equivalent in any language) are listed. 
  • GreyNet International - A selection of web based resources in Grey Literature. Also contains the OpenGrey Repository.
  • Grey Literature Report - a publication produced by the The New York Academy of Medicine between 1999 - 2016, alerting readers to new grey literature publications in health services research and selected urban health topics.