Information sources: Grey literature

Finding grey literature

Grey literature, due to its diverse origins and unpublished nature, can be difficult to find.  It is often found by searching for the agency or institution who is most likely to produce the literature. The search may require looking at a large number of sources. 

Here are a few places to start looking:

  • Start your search by choosing from the options listed below.
  • Search the corporation, institution, or agency that is most likely to produce the type of information you are looking for.
  • Search online catalogues.
  • Consult your academic liaison librarian.

What are the features of grey literature?

  • Grey literature is created by practitioners, rather than academics.
  • It is rapidly produced, so can be very current.
  • It might be very detailed and geographically specific.
  • It is often intended for small or specific audiences.
  • It can be difficult to find.
  • it is not peer reviewed, so will need to be evaluated carefully for authority, accuracy, objectivity and significance.

This helpful AACODS checklist from Flinders University, has been designed to enable evaluation and critical appraisal of grey literature.

Places to search for grey literature

Searching the online catalogue of large libraries for grey literature can be fruitful.

Academic conferences are events where people present news about their recent research and findings. Many conferences are held annually, sometimes at a different location each year. The conference organisers often collect the presented papers and publish them as the conference proceedings.

Contacting authors, peer groups and private companies can sometimes be a way of tracking down difficult to find grey literature. This can be done through:

  • written correspondence
  • email discussion lists
  • social networks, such as ResearchGate, and LinkedIn
  • If you are in health or social care, try CHAIN - Contact, Help, Advice and Information Network
  • NHS people may join NHS Networks - click on the Connect tab to find people with similar interests.

Theses often contain cutting-edge material.  In many cases the information may not have made its way into published journal articles or books.

Since there are two accepted spellings, to locate information on gray/grey literature in general, search for: (gray OR grey) literature.

Most of the grey literature available on the Web is in the form of PDF documents so can save time by typing filetype:pdf after your keywords. Also consider restricting your search to the .org and/or .gov domains, e.g. type site:org after your search terms.

What is grey literature?

Grey literature refers to both published and unpublished research material that is not available commercially. It is often of a scientific or technical nature and is not available through the usual bibliographic sources, such as databases or indexes.

It is produced by government departments, universities, corporations, associations and societies, and professional organisations.

Some examples:

  • technical reports
  • standards
  • conference proceedings
  • newsletters
  • government documents
  • white papers
  • patents
  • bulletins

Why use grey literature?

Grey literature is an important source of information. To carry out a thorough search of the literature in your area; a systematic review, it is essential to search for material which has not been published. 

Though not scholarly, it is produced by researchers and practitioners in the field.  It can often be produced more quickly, therefore being more current, and be more detailed than other types of literature.

In addition, it can reduce positive publication bias - negative results are often reported in the grey literature but not in published work.