Grey Literature (in the Health Sciences)

The resources on this page provide a general starting point to searching for grey literature.

Here you will find links to databases that specifically collect and index grey literature documents.  The search engines found on this page have been designed to conduct  broad searches across global databases, including the deep web.  The preformulated search strategies have been designed to filter for specific types of grey literature such as non-governmental documents.

The resources below contain lists of the many databases that can be searched for grey literature.

These resources broadly collect and index grey literature such as white papers, policy documents, summaries and more on global health topics. Resources are grouped geographically (American, European, etc). Resources requiring USC login are listed last.   

PubMed databases, features, and preformulated search strategies.

The search engines below function similarly to Google, but contain features and filters useful for retrieving globally dispersed grey literature documents. These resources are organized first by broadest global perspective, and then by range of topic coverage from broadest to narrowest.  

Google databases and preformulated search engines can be helpful for finding some grey literature. However, please keep in mind, as with all other tools/resources, no one resource can be completely comprehensive.  Many creators of grey literature websites may block Google from accessing their sites, or, are not chosen to be indexed by Google. As such, researchers should consider using other specialized grey literature search engines or resources in addition to the below. 

Tips for searching Google Scholar for Evidence Synthesis Grey Literature Search 

• Determine scope of searching:
  • See additional workflow tips under Where to Begin?
  • Do test searches to determine if best to use one search strategy, or multiple smaller search strategies using a variety of keywords.
  • Establish screening parameters ; i.e. limit to first 5, 10, 20 pages, / 100 results, etc. 
  • Suggest setting aside time to conduct search in one sitting, due to limitation of having to add each citation one by one to My Library. 
• Set up Google Scholar:
  • Use incognito / private browser setting to mitigate impact of search engine personalization on results.
  • Sign in to Scholar in order to save items to My Library and export to a reference manager.
  • Change results to display 20 items per page: Menu / Settings / Results per page.  
  • Add USC Find It link for full text: Menu / Settings / Library links / search ‘USC’ / Save.
• Searching:
  • Scholar does not support truncation to search multiple root endings.; i.e. injur* You will need to type out each variation; injury|injuries|injured.
  • Use quotation marks around phrases (two or more words) to obtain results where words are next to or near each other. 
  • Search strings are limited to 256 characters.
    • Replace “OR” with vertical line. AND is assumed by a space.   
  • Run a search or multiple searches.
    • Run one search and look through the first 200 citations (or more if find it necessary).
    • Multiple searches will contain overlap across results. If you save citations from one search, these citations will remain selected when you run a new search so you can easily see if there are new items within subsequent searches.

Sample search 1: nursing ("Healthcare Disparities"|"Cultural Competency"|"Culturally Competent Care"|competent|competence|competency|competencies)

Sample search 2: (nurse|nursing) ("cultural competency"|"competent care")

• Saving citations:
  • Click “star icon / Save” under citation.
  •  Click “+ Create new” to create folder – name it in an identifiable way: Title_Date
  • Unfortunately, you do need to add each citation one by one.  No way to select multiple citations and then add altogether.

• Download citations:
  • Go to ‘My Library’.
  • Select folder.
  • Click ‘arrow ’ to download citations to reference manager, or CSV file.

These resources can be used to get in contact with researchers or to search for protocols, unpublished study information, or pre-prints.