Searching the literature: bibliographic databases

Once you have defined your search concepts and thought about your search terms, you can begin searching for your systematic review. We suggest you start your search by using relevant subject databases and then consider adding other searching approaches such as following a citation trail or extending your search to include grey literature, and specialist resources such as clinical trials registers. Searching one database at a time enhances your search by making full use of the available subject indexing and search functionality.

Systematic reviews should encompass a wide range of information sources.


Searching databases

Search skills for bibliographic databases are described on the ‘Studying Effectively: Search skills for bibliographic databases and online catalogues’ web pages.  

The online resource Searching systematically to find evidence for a systematic review includes demonstrations of how to run searches in various databases.  

Subject databases

Search collections of articles by subject. Please read our list of suggested databases for different subject areas and the faculty-specific subject guides. Researchers at UoN can access these databases through our discovery tool, NUsearch.

Note that some databases use subject headings which enable you to search using controlled vocabulary terms, e.g. MeSH (used in MEDLINE, PubMed, Cochrane), Emtree (used in Embase).

Citation searching

Track individual research articles forwards and backwards in time. The following databases are excellent for this purpose:  

Learn more about citation searching.

Grey literature and other

Grey literature is research which appears in a non-commercial or unpublished form. Below are some sources you can consider:

  • Theses/dissertations. For worldwide coverage, try ProQuest Dissertations & Theses; for European coverage, try DART-Europe; and for UK theses, you can use EThOS (all three resources are available via NUsearch).
  • OpenGrey
  • Google Scholar
  • Reports and guidelines (e.g. NICE).
  • For clinical trials, try the  WHO International Clinical Trials Registry Platform, an international registry of clinical trials, and/or, a US registry of clinical trials.
  • Hand searching specialist journals not indexed in the subject databases.

More information on grey literature is available in the King's College London LibGuide on systematic reviews.


Further resources for using specific databases

For an introduction to systematic searching in PubMed, see the online PubMed course (1 hour long) produced by Douglas Grindlay in the School of Medicine, University of Nottingham.

For a help with searching databases such as MEDLINE, Embase and PsycINFO, all available through the Ovid platform, use the online tutorials. Locate them by logging into the OVID platform, then click on the ‘Support and training’ link at the top right of the page. Navigate to the ‘Training’ section in the left-hand menu and browse through the resource-specific tutorials.

Dealing with your search results

Read our guidance on how to manage the references you identify whilst searching.

Saving searches and alerts

Many databases enable you to save searches and set up alerts.   

  • Saving searches means they can be re-run at the touch of a button, rather than retyping your terms from scratch.
  • Alerts provide you with automatic updates when new, relevant articles are added to a database.

You can stay up-to-date with individual journal titles in your field by requesting a table of contents alert from the British Library's Zetoc service.  Once you’ve registered, the table of contents for your journal of interest will be sent straight to your inbox as soon as it is published.

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