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Systematic Reviews - Research Guide

Locating Grey Literature

What is Grey Literature?

The term grey literature "is usually understood to mean literature that is not formally published in sources such as books or journal articles" (Lefebvre, Manheimer, & Glanville, 2008, p. 106).

 Grey literature may include multiple types of document produced on all levels of government and by academics, businesses and organisations  in electronic and print formats where publishing is not the primary activity of the producing body. (Greynet, 2015.)    

Examples are:

  • reports (reports of government and research organisations are generally freely available on the internet)
  • theses
  • conference proceedings
  • technical specifications and standards
  • translations
  • technical and commercial documentation
  • official documents
  • Newsletters, emails, blogs and other social networking sites an be considered as community based examples of grey literature

There may also be grey literature that is specifically relevant to your discipline. Practice Guidelines are highly relevant to nursing and health professions, working papers are used in the social sciences (particularly economics) and patents are important to engineering.

A systematic review conducted in 2008 by members of the Cochrane methodologies team found that often the results from grey literature significantly affect the outcome of a review, as they often report more negative or inconclusive data than published journal articles (Hopewell et al., 2008). As such, it is important to treat grey literature as another potential source of studies for inclusion while noting that it is usually not subject to peer review and must be evaluated accordingly.


References

1. Alberani, V., De Castro Pietrangeli, P. & Mazza, A.M.  (1990).  The use of grey literature in health sciences: A preliminary survey.  Bulletin of the Medical Library Association, 78 (4) : 358-363. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC225438/ 
2. GreyNet International (2015). Retrieved from http://www.greynet.org
3. Lefebvre C, Manheimer E, Glanville J. (2008). Searching for studies. In: J.P.T. Higgins & S. Green (Eds.), Cochrane handbook for systematic reviews of interventions. Chichester: Wiley-Blackwell.
4. Hopewell S, McDonald S, Clarke M, & Egger M. (2007). Grey literature in meta-analyses of randomized trials of health care interventions. The Cochrane Library.  doi: 10.1002/14651858.MR000010.pub3

Where to Find Grey Literature

Theses

University repositories can be used to locate theses, research papers and data if they have been made available. You can find information about locating theses and dissertations in the Murdoch Library Theses Guide.

The Murdoch Research Repository is an open access digital collection of research created by Murdoch University staff and students. 

OpenDOAR is an authoritative directory of academic open access repositories.


Australian Government Information

Government Departments (State and Commonwealth) can be found with Google. Some useful sites are listed below:


International Sources

Tips for Searching for Grey Literature

In addition to the sources listed above, internet searching can locate other useful sources:

  • If looking for information on grey literature in general, remember there are two spellings and search for (gray OR grey) literature
  • Find and search the online catalogues of large libraries
  • Conference papers or conference proceedings can be difficult to track down - search for the host sites of conferences and academic associations
  • You can search for conference papers in the Web of Science Core Collection - at the search page select More Settings and then select only the proceedings indexes
  • Try restricting your search to the .org and/or .gov domains

Evaluating Grey Literature

You should evaluate grey literature as you would all information to be included in your research:

  • Authority - Has the report come from a reputable institution or organisation?
  • Accuracy -  Is it supported by documented and authoritative references? Is there a clearly stated methodology?
  • Currency - Check the date to make sure it fits with your purpose avoid if no date can be found
  • Coverage - Have limitations been imposed and are these stated clearly?
  • Objectivity - Can bias be detected? Look carefully at commercial or political sources
  • Significance - Is it relevant? Would it enrich or have an impact on your research?