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Medline Training: Combine Search Terms

AND or OR?

To search for more than one term at a time, you must use Boolean operators. The two most commonly used operators are AND and OR.


Use AND to retrieve items that have BOTH terms, not just one or the other. The red area in the diagram below indicates that using AND would retrieve items that have both the term headache AND the term aspirin.


Use OR to retrieve items that have one or more of the terms listed. The red area in the diagram below indicates that using OR would retrieve items that have the term acetaminophen OR the term aspirin, OR both.


Combine your search terms

After you have searched for several terms, select the ones you want to combine by checking off the boxes beside them, then click on the AND or OR button below the list of searches. In this example, by selecting AND the only items that will come up in the results have all three of the subject headings 'Length of Stay' AND 'Cross Infection' AND 'Methicillin-Resistant Staphylococcus aureus'

Check the results

The combined search will be added to the list of searches. Click on 'display', or scroll down the page, to see the results.


If you find an article that is on topic, you can click on 'Complete Reference' to look at the record to see what subject headings were assigned to it, then do a search for any additional subject headings that would be useful. You can use the combining process to mix and match search terms to modify your results.

Video: Boolean Operators

Video: Combining YourTerms