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Physical Therapy

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

Using Google to Locate Grey Literature

Google searching can be a useful tool for finding documents that are not indexed in traditional databases, or even GoogleScholar.  Leveraging some of Google's advanced searching features can help optimize a search.  

Exact Phrase

Using quotation marks asks Google to locate an exact phrase

For instance: health insurance "policy brief"

This search will only retrieve results that contain the specific phrase "policy brief"

Site Search

Use the site search function to ask Google to look in a specific site, or a specific kind of site.  

For instance: health insurance 

This query will retrieve results only from sites that have an .edu domain.

You can also perform a site search on a specific website. 

For instance: drug costs

This query will look for any mention of drug costs on the Kaiser Family Foundation website

File Type Search

Use the file type search function to ask Google to retrieve a specific kind of file. 

For instance: "policy brief" filetype:pdf

This query will only return links to PDFs that mention "policy brief" in the document.  Also consider filetype: filetype:doc for Microsoft Word Documents, filetyple:xls for Excel files (which might be useful if you're looking for raw data), or filetype:ppt if you're interested in locating PowerPoint presentation materials.  

Search Operators

Google automatically places AND between search terms, but you can use OR to combine queries where either term would be relevant. 

For instance: drug OR pharmaceutical

You can exclude terms from your search using the minus sign (-). 

For instance: drug -marijuana

This query will retrieve only hits that don't contain the word marijuana.

See Google Search Help for more ways to tailor your queries.  

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