Gray Literature

Essentially, gray literature is material that has not been published in the way that a book or a journal is published, but is nevertheless available (and useful!) to researchers. It is often included in systematic reviews as a way to round out the results and reduce bias.

The following are some more in-depth definitions of gray literature.

• “Documentary material which is not commercially published or publicly available, such as technical reports or internal business documents,” (Oxford English Dictionary, n.d.).
• “Documentary material in print and electronic formats, such as reports, preprints, internal documents (memoranda, newsletters, market surveys, etc.), theses and dissertations, conference proceedings, technical specification and standards, trade literature etc., not readily available through regular market channels because it was never commercially published/listed or was not widely distributed,” (Farace & Schöpfel, 2010).
• “Term often used for semi-published literature, i.e. literature which is not formally listed or priced but is nevertheless in circulation, such as institutional reports. Such literature is often difficult to trace,” (Keenan & Johnston, 2000).

ERIC is a database that provides several different types of publications. To narrow your search to gray literature, look for the Publication Type field on the Advanced Search page.

Helpful categories to select include:

• Conference proceedings
• Dissertation
• Government document
• Report

To select multiple categories, hold down the Ctrl key (Windows) or the Command key (Mac) while you select them.