Systematic Review

What is grey literature?

Grey literature is the term used for information “produced on all levels of government, academics, business, and organization in electronic and print formats not controlled by commercial publishing”. (GreyNet)

Grey literature includes but is not limited to:

  • Theses and dissertations
  • Clinical Trials
  • Newsletters
  • Reports
  • Standards
  • Conference proceedings
  • Video's
  • Emails
  • Blogs

Why should I look at grey literature?

Researchers should always consider grey literature when undertaking a systematic review. The information available via this avenue is important in showing that researchers have taken a rigorous approach to searching all the evidence available in answering the research question.

Some of the information that can be found in searching grey literature are results from studies where the trial or study indicated a negative impact or no effect in the results. Papers or reports which have a less than positive outcome are less inclined to be published in scholarly journals, this known as publication bias.

As research takes a long time from initial planning to publication, study results are often presented at conferences giving researchers the opportunity to disseminate their findings before appearing in a peer-reviewed publication.


Note: Researchers who use grey literature when undertaking a systematic review need to ensure the information is credible and does not show bias.

Jess Tyndal from Flinders University developed the AACODS checklist (Authority, Accuracy, Coverage, Objectivity, Date, Significance) to assist in evaluating grey literature.

Where to search!

For researchers there are a number of challenges around grey literature such as locating documents not published on the web or older documents not archived.


So how do you find grey literature?

The following links may assist you in finding grey literature to assist in answering your research question.


Clinical Trial Registers

Cochrane Central Register for Clinical Trials (CENTRAL)

Australian New Zealand Clinical Trials Registry (ANZCTR)

NHMRC Clinical Trials Centre

Open Trials


WHO International Clinical Trails Registry Platform

EU Clinical Trials Register


Conference presentations


Grey literature Indexing Databases

Analysis & Policy Observatory (APO) – Australian public policy and articles from academic research, government and non-government organisations.

MedNar – a medical- focused search engine which retrieves results in real-time from authoritative public and deep web resources.

OAIster Database - a union catalog of millions of records that represent open access resources. OAIster includes more than 50 million records that represent digital resources from more than 2,000 contributors.

OpenDOAR -  OpenDOAR is the quality-assured global directory of academic open access repositories. It enables the identification, browsing and search for repositories, based on a range of features, such as location, software or type of material held.

Open Grey - a multidisciplinary European database, covering science, technology, biomedical science, economics, social science and humanities.

PsycEXTRA – a curated and index of hard-to-find content from authoritative sources. Researchers will find information on resources such as the latest conference proceedings, reports, patient-oriented factsheets, monographs, standards and guidelines. – access to over 200 million pages of authoritative U.S. federal science information including research and development results. - global science gateway comprised of national and international scientific databases and portals.

Google Scholar



The Theses Library Guide provides details on how to access CQ University higher degree theses as well as Australian and International theses.


Web searching

MedNar – a medical- focused search engine which retrieves results in real-time from authoritative public and deep web resources.

Google Scholar - check out the following YouTube clip - Finding Grey Lit: Google Scholar from Lister Hill Library Tutorials.