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Grey Literature

This guide introduces you to grey literature, why you might use it in your research and how to find different types of grey literature.


On this page you can find out what is meant by grey literature and examples of different types of grey literature you may come accross. It also highlights why you might want to use grey literature in your research but also what to watch out for when using grey literature.

If you want to know how to search for and find grey literature click on Finding grey literature below or in left-hand menu.

What is grey literature?

The term 'grey literature' refers to a wide range of information which is not formally or commercially published, and which is often not well represented in library research databases.


While there are a number of definitions for grey literature, in the academic community a widely accepted definition is

information produced on all levels of government, academia, business and industry in electronic and print formats not controlled by commercial publishing i.e. where publishing is not the primary activity of the producing body.

From: Third International Conference on Grey Literature in 1997 (ICGL Luxembourgh definition, 1997 - Expanded in New York, 2004).

Examples of grey literature

Grey literature is usually produced by government departments and agencies, local authorities, academic institutions, professional organisations, research groups, think tanks, charities and comes from many other sources.


Not all of these examples listed will be relevant to all researchers. The primary grey literature in the sciences may differ from grey literature in the arts and humanities. Have a think about the types of information you are interested in before you begin searching.


Examples include:

  • Blogs
  • Clinical trials
  • Company information
  • Conference papers and proceedings
  • Datasets
  • Dissertations and theses
  • Government documents and reports
  • Interviews
  • Lectures
  • Market reports
  • Newsletters
  • NGOs documents and reports
  • Patents
  • Policy statements
  • Research reports
  • Standards
  • Statistical reports
  • Tweets
  • White papers, working papers

Why use grey literature in your research?

To find current and emerging research: Formally published research can take time going through lengthy peer review and editorial processes unlike materials such as trial registers, pre-prints and working papers which provide details of ongoing research. Upcoming research can also be found in conference proceedings as conferences are often where new research is first announced.


To broaden your research: Innovations from the private sector, policy from government and engagement with the public as patients or beneficiaries of research will not generally be published in academic journals and books. Policy documents, industry papers and social media will help you keep up to date with social and economic updates in your field.


To mitigate against 'publication bias': Studies showing positive research results are much more likely to be published in journals. A search for grey literature will help to ensure that all relevant results, even if negative, are located. 


To find viewpoints of individuals, such as patients and consumers. 


To find more in depth or practical coverage of topics: Research results may be more detailed in primary source reports and documents. 


To access unpublished conference proceedings and research.


Things to watch out for

  • Grey literature sources can vary hugely in terms of quality. 
  • Grey literature can be regarded as less prestigious and less organised than published literature as is not always peer reviewed or fully edited.
  • It may include raw data and findings that are incomplete. 
  • Papers, briefing documents and fact sheets, etc. from organisations might not always be unbiased. 
  • Grey literature is often not formally published so you need to consider the longevity of the resource. E.g. something may be available on the web, or a blog for a short period only and may not be formally archived.
  • Make sure you keep a record of material you wish to use/reference - as it may not be there for discovering later down the line.