Skip to Main Content

Physical Therapy

Guide to locating research evidence and tools for Physical Therapy students and faculty.

What is Grey Literature?

"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." (Luxembourg, 1997 - Expanded in New York, 2004,

Grey literature may contain valuable information that cannot be found in academic journals.

Grey literature varies in terms of quality, and it is not always subject to a formal review process. As with any information source, it is important to review it carefully.

  • Who produced this source?
  • How do they know what they say they know?
  • Why are they providing this information?
  • What research methods did they use?
  • Who is funding their research?
  • How current is this source?
  • What perspectives and biases might the author have?

Grey Literature may exist in any number of formats:

  • reports
  • preprints
  • conference abstracts and proceedings
  • white papers
  • theses, bibliographies
  • pamphlets
  • official documents
  • newsletters
  • trial registrations
  • patents
  • informal communication (that may include interviews, blog postings, podcasts, personal communication such as email)
  • website information
  • web repositories
  • and more!

 Read more about grey literature:

Sources for Locating Grey Literature:

The following collections of resources offer suggested search engines or databases that can be used to look for different types of grey literature:

Meetings & Conference Proceedings

Research In Progress

Clinical Trial Registries


Reports, Open Archives & Repositories

Theses & Dissertations