Grey literature is "Information produced on all levels of government, academics, business and industry in electronic and print formats not controlled by commercial publishing i.e. where publishing is not the primary activity of the producing body.
CGL Luxembourg definition, 1997-expanded in New York, 2004
Grey literature is published informally or non-commercially, or remains unpublished. It can appear in many forms, including government reports, statistics, patents, conference papers and even non-written resources such as posters and infographics.
Grey literature has not usually been peer reviewed, but may still be good, reliable information.
It is produced from a variety of sources including industry, think tanks, and government departments, and is usually not indexed or organised which can make it difficult to locate.
Grey literature differs from "black literature" which is the familiar peer-reviewed publications found in commercial publishers' databases.
Grey literature could be used as a primary or secondary source.
A short video explaining grey literature from Western Universities library
Grey literature is used in research because:
|Technical Reports||Theses and dissertations|
|Government documents||Research Reports|
|Clinical trials and practice guidelines||Blogs|
|Informal communications||pre and post print articles|
|White papers||Working papers|
For a comprehensive listing of grey literature types view the greynet.org table.