The Literature Search
- A systematic review search includes a search of databases, gray literature, personal communications, and a handsearch of high impact journals in the related field. See our list of recommended databases and gray literature sources on this page.
- a comprehensive literature search can not be dependent on a single database, nor on bibliographic databases only.
- inclusion of multiple databases helps avoid publication bias (georaphic bias or bias against publication of negative results).
- The Cochrane Collaboration recommends PubMed, Embase and the Cochrane Central Register of Controlled Trials (CENTRAL) at a minimum.
- Gray Literature is the term for information that falls outside the mainstream of published journal and mongraph literature, not controlled by commercial publishers
- hard to find studies, reports, or dissertations
- conference abstracts or papers
- governmental or private sector research
- clinical trials - ongoing or unpublished
- experts and researchers in the field
- Gray Literature Sources
- Library catalogs
- Professional association websites
- WorldCat - 1.5 billion items in this collection of library catalogs
- Google Scholar - Search scholarly literature across many disciplines and sources, including theses, books, abstracts and articles.
- Dissertation Abstracts - dissertation and theses database - NIH Library biomedical librarians can access and search for you.
- NTIS - central resource for government-funded scientific, technical, engineering, and business related information.
- AHRQ - agency for healthcare research and quality
- World Health Organization - providing leadership on global health matters, shaping the health research agenda, setting norms and standards, articulating evidence-based policy options, providing technical support to countries and monitoring and assessing health trends.
- List Gray Literature Producing Organizations - from the New York Academy of Medicine, includes government and private sector
- Gray Source Index
Clinical Trial Registries
- International Clinical Trials Registery Platform - from the World Health Organization
- Australian New Zealand Clinical Trials Registry
- Brazilian Clinical Trials Registry
- Chinese Clinical Trial Registry-
- ClinicalTrials.gov - U.S. and international federally and privately supported clinical trials registry and results database
- Clinical Trials Registry - India
- EU clinical Trials Register
- Japan Primary Registries Network
- Pan African Clinical Trials Registry
NIH Library Service: