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Systematic Reviews: Grey Literature


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What is Grey Literature?

Grey Literature is a field in library and Information science that deals with the production, distribution, and access to multiple document types produced on all levels of government, academics, business, and organization in electronic and print formats not controlled by commercial publishing i.e. where publishing is not the primary activity of the producing body. Our purpose is to direct you to health sciences focused literature that might otherwise be lost because it is not indexed in our commonly used tools such as PubMed, CINAHL, Web of Science, etc. 

Why Search Grey Literature?

  • Impacts publication bias
  • Can alleviate the effect size of study interventions
  • Enhances the level of evidence

Search Methods

  • Hand Search of journals in the field - which journals are important in this field?
  • Citation Search - which papers have cited this article?
  • Bibliographies of Articles - what other papers does this author cite?
  • Pertinent Authors - who is important in this field?

Resources for Grey Literature

Evaluate Grey Literature

Evaluating grey literature can be difficult because many of the standard indicators of quality, such as the reputation of the author, can be missing.

The AACODS Checklist is a well known and widely accepted instrument that you can use to assess what you find. It is made up of the following 6 elements:

  • Authority: Is the author credible?
  • Accuracy: Is it supported by documented and authoritative references? Is there a clearly stated methodology? Is it 'in line' with other work on the same topic?
  • Coverage: Have limitations been imposed and are these stated clearly?
  • Objectivity: Can bias be detected?
  • Date: Can't find the date? Avoid materials without dates
  • Significance: Is it relevant? Would it enrich or have an impact on your research?


This material is quoted from "Grey/Gray Literature: What is Grey Literature?" a guide composed by Kathleen Carlson.

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