Grey Literature is any literature that has not been published through traditional means. It is often excluded from large databases and other mainstream sources.
Leaving grey lit out of a systematic review excludes a major section of the available research. To avoid bias and to ensure that the review is as thorough as possible, always search grey literature.
CADTH's "Grey Matters" guide lists many resources. As well, the CRD guide and Chapter 6 of the Cochrane Handbook mentioned earlier in this guide include links to a number of grey literature sources.
Grey Literature Search Tips:
Appraising Grey Literature:
Students conduct both systematic reviews and original studies for their theses and dissertations. These texts are not usually included in major databases.
U of T’s Theses and Dissertations in the Sciences research guide is an excellent resource, with links for both U of T theses and dissertations and those from other institutions.
Conferences are nodes of new research, often featuring studies before they appear in journals.
This list provides only a few producers and collectors of grey literature. Do a thorough search for sources in your field.
Many institutions have institutional repositories, online databases of publications by their members. These can include publications by faculty and student dissertations and theses.
Government bodies frequently publish reports and studies on topics relevant to health science. In Canada, government bodies at both the national and provincial levels produce relevant material.
“Newspapers B&W (4),” NS Newsflash
Newspapers and magazines can be helpful sources of non-academic information.
U of T's research guide on Newspapers includes thorough information and some databases that also index magazines. You can also look up individual magazines in the library catalogue to determine our access.
Sometimes, the best way to find grey lit is to search the Web. Different search engines have their own search algorithms that will pick up different results.
When searching Google, it helps to use versions from different countries. If you are looking for grey lit from the UK, for example, use Google UK to find results from that country. Check this list of all Google domains for different countries.
Another useful search engine is Duck Duck Go. Duck Duck Go does not collect user information and therefore results are not filtered based on your personal profile.
“keyboard detail view – macro,” photosteve101
Often, writers of systematic reviews find that some data is left out of studies. In such cases, a good option is to contact the author of the study.
Experts in the field can also be rich sources of information. Talk to an expert to find out:
Gerstein Science Information Centre
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Toronto, ON, M5S 1A5
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