Register Reset Password Skip to main content

Grey literature: Searching the grey literature

Grey literature resources

What is grey literature?

'Grey literature' is defined as "that which is produced on all levels of government, academics, business and industry, in print and electronic formats, but which is not controlled by commercial publishers." This is the Luxembourg definition, developed and approved during the Fourth International Conference on Grey Literature in 1999.

The value of grey literature has been formally acknowledged by the evidence-based research organisations, the Cochrane Collaboration, the Campbell Collaboration and the Joanna Briggs Institute, all of whom require their reviewers to also search the grey and unpublished resources in order to avoid publication bias.

Examples of sources of grey literature

Conference papers




Research reports


Book chapters

Annual reports


Policy statements


Government documents



Press releases

Clinical practice guidelines

Clinical trials

Working papers




Fact sheets


Informal communication eg Blogs, podcasts, email


Patient handouts


How to search and evaluate the grey literature

Google Advanced Search can be used to effectively search the web for grey literature.

The AACODS checklist was designed by Jess Tyndall to enable evaluation and critical appraisal of grey literature and has the flexibility to be applied to a wide range of resources.

AACODS (Authority, Accuracy, Coverage, Objectivity, Date and Significance)

  • Authority: Is the author credible?
  • Accuracy: Is it supported by documented and authoritative references? Is there a clearly stated methodology? Is it 'in line' with other work on the same topic
  • Coverage: Have limitations been imposed and are these stated clearly?
  • Objectivity: Can bias be detected?
  • Date: Can't find the date? Rule of the thumb is to avoid such material
  • Significance: Is it relevant? Would it enrich or have an impact on your research?

Further information

Canadian Agency for Drugs and Technologies in Health, Grey matters: a practical search tool for evidence-based medicine
Health librarians and grey literature: what do we need to know? / invited lecture presentation and notes by Jess Tyndall, Medical Librarian, Flinders University. Presented Royal Melbourne Hospital, July 15 2014 and Royal Adelaide Hospital, September 25 2014.

Primary Health Care Research & Information Service, Introduction to ... accessing the grey literature

Tyndall, J. AACODS Checklist , Flinders University, 2010.

University guides on searching the grey literature
LaTrobe University Grey literature for health sciences
MacQuarie University Systematic reviews - grey literature
University of Canberra Grey literature searching in health
University of Newcaste Systematic reviews - grey literature
University of WA Systematic reviews - grey literature