Evidence Synthesis

The Cornell University library defines grey literature as

...Literature produced by individuals or organizations outside of commercial and/or academic publishers. This can include information such as government reports, conference proceedings, graduate dissertations, unpublished clinical trials, and much more. The sources you select will be informed by your research question and field of study, but should likely include, at a minimum, theses and dissertations.

Grey literature is important for an evidence synthesis project as the aim is to synthesize all the available work that is applicable to your specific research question. While not peer-reviewed, grey literature represents a valuable body of information that is critical to consider when synthesizing and evaluating all available evidence.

• Refer to grey literature sources used for related evidence syntheses Refer to both published evidence syntheses and registered protocols. 
• Search databases that specialize in grey literature There are a number of databases that specialize in grey literature. 
• Search for theses and dissertations There are a number of databases dedicated to theses and dissertations, which you can search using your search terms. See the "Grey Literature Sources" box at the bottom of this page for links to these resources. 
• Search clinical trials There may be clinical trials being conducted that are relevant to your research question, but that haven't been published yet or never were published. See the "Grey Literature Sources" box at the bottom of this page for links to these resources. 
• Identify government agencies and international and non-governmental organizations that might publish technical papers and reports on your topic.  Search their websites or any online libraries that they may provide. See the "Grey Literature Sources" box at the bottom of this page for links to some examples.
• Search conference proceedings and newsletters Identify professional organizations that have and/or conferences at which researchers might be presenting work related to your topic. 
• Contact known researchers in the field to determine if there are any ongoing or unpublished studies that s/he may be aware of.

• Networked Digital Library of Theses and Dissertations (NDLTD)

NDLT is a free international resource for theses and dissertations.

• Center for Research Libraries (CRL)

CRL is a resource for institutions outside of the U.S. and Canada.

• Australia New Zealand Clinical Trials Registry

The ANZCTR is an online register of clinical trials being undertaken in Australia, New Zealand and elsewhere.

• Clinicaltrials.gov

The US registry for clinical trials. Includes new, ongoing, and completed human clinical trials both in the US and countries around the world.

• World Bank

The World Bank now makes all of their publications openly available online.

• Grey Matters

Grey Matters is an online manual that provides a thorough list of sources for grey literature in medicine and a helpful checklist to help systematize your process. (Requires free account)

• Searching the grey literature: A handbook for searching reports, working papers, and other unpublished research