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Systematic Reviews

This Guide describes the steps involved in a systematic review.

Gray Literature

Gray Literature

Gray literature is an information source that is, often, not readily available via traditional publishing methods.  For instance, abstracts of conference proceedings, where papers are presented to a live audience but the papers themselves may not be formally published in the academic literature.

Gray literature sources at the National Library of Medicine.


Examples of Traditional Gray Literature include:

  • Completed clinical trials
  • Dissertations
  • Conference Proceedings
    • OCLC/ProccedingsFirst -- (192,000+ records, 1993 - Present -- conference proceedings, meetings, congresses, symposia, exhibitions, workshops.)
    • Scopus -- (Over 8 million conference proceedings from nearly 100,000 conferences.)
    • Web of Science -- (The Conference Proceedings Citation Index contains over 227,000 conference proceedings, with 70 million cited references dating back from 1990 to present.)
  • Posters/papers
  • Governmental reports
    • International, National, Local
  • Guidelines and position papers
  • Preprints
  • Reports
  • Statistical data
  • More at:

Potential New Sources for Gray Literature:

  • Google Scholar
  • Blogs
  • Toolkits
  • PowerPoint presentations
  • Pamphlets/factsheets
  • Tweets

*Source: Bonato, Sarah, MIS. "Going Grey with Google Scholar for Systematic Reviews MLA Webinar," November 17, 2021.