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Health Sciences Advanced Search

This guide is designed from postgraduate level students working on primary research projects or dissertations.

Gray Literature

Not all research literature is contained in databases. Some important research literature will be found in file cabinets, on office shelves, in newsletters, on the internet, etc. This literature is formally labeled Gray Literature

Gray Literature Pyramid with examples

Gray literature is literature or research does not go through the traditional publication process. 

You have to hunt for Gray literature yourself.

  • Gray Literature publications are non-traditional.
  • Instead of going through the usual commercial publication process, authors may self-publish their articles (or research reports) directly to the Internet. And some research is uploaded to special websites called Repositories. 
  • Similarly, professional organizations, foundations, or societies sometimes publish articles, white papers, and research reports through their own online publications.  (ex. Pew Reports; Robert Woods Johnson Foundation, AARP, JAMA Network, etc.)
  • Government agencies are required publish government documents and research reports on government websites so the general public can access them freely.

Search Engines can find this literature, but only if the Gray literature websites display the content close enough to the top layer of a website, and not behind a search box or pay wall.

Gray literature is the ultimate Deep Web content. And it sometimes requires Advanced Search Skills + Expert Knowledge to locate it. You have to know a website exists and how to get to it.


  • Global HIV Prevention Working Group
  • GBC Health
  • WHO
  • HHS
  • CDC
  • United Nations, Joint Programme on HIV/AIDS (UNAIDS)
  • National Academy of Sciences, Institute of Medicine

Now, go to Google, locate the websites of each of these organizations, and then type in HIV prevention into their organizational website Search Box. See if you uncover something interesting...

This kind of search is round-about, willy nilly, get-what-you-get type of search, but it works. Gray literature: it's hit and miss.

The University of Michigan and the University of Illinois at Urbana-Champaign have excellent websites on Gray Literature with loads and loads of places to search. See links below:

The PHPartners website offers a Structured Evidence Queries tool that links directly to Healthy People 2020 Objectives which provides a professionally crafted PubMed Database Search Strategy ready for you to just click on go.

Healthy People 2020 Structured Evidence Queries

Healthy People 2020 Structured Evidence Queries

Health People 2020 Objectives + PubMed Search

Healthy People 2020 Objectives + PubMed Search