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HHPF 502: Introduction to Research

Get Better Search Results!

When searching in databases, there are many advanced search strategies that can help you narrow or broaden your search results. You may know the basics, like narrowing by publish date or language, but below are further strategies that will help you get the best possible search results.

Boolean Operators

This graphic was created by Prince George's Community College Library. 


Truncation shows results for multiple versions of a search term by searching a shortened version of the term followed by an asterisk.

For example, searching preven* would show search results for prevent, prevents, preventing, and preventative.


Similar to truncation, wildcards are symbols inserted into your search terms. 

A question mark (?) can be used to represent a single, variable character. For example, m?n would search for men and man.

An asterisk (*) can be used to represent an unknown number of characters. It can be used between terms that may include an unknown term, or within a word that could have alternate spellings. 

Advanced Search Strategies

Unlike keywords, Subject Headings are the major content in the article; they're also called "controlled vocabulary." A search on the topic altitude training as a keyword may retrieve some articles with 'altitude,' some with 'training' and some with the phrase 'altitude training.' But if the subject heading is 'altitude training' then the article is focused on that topic. Your search may be much broader retrieving more articles with keywords, but in searching with subject headings, you are likely to get fewer but more precise results. Subject headings are also referred to as 'descriptors' in some databases.

More specifically, PubMed and MEDLINE utilize Medical Subject Headings (MeSH), a controlled vocabulary created by the National Library of Medicine.


Some databases have a thesaurus - a powerful collection of subject headings or standardized terms created by the indexers. Controlled vocabulary provides more effective searching capability in databases where a thesaurus is available. For example you may think of the word 'substance abuse,' but the database thesaurus indexes it as 'drug abuse.'

Use the thesaurus to find keywords and phrases and apply these search terms in the subject field (SU or DE).  The results may be better for searches of thesaurus terms in the subject field than for a simple keyword search of the title or abstract of an article.

Make sure to consult the following thesauri when searching these databases:

MEDLINE- MeSH terms (Medical Subject Heading)

CINAHL - subject headings

PsycINFO - thesaurus from APA