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Nursing and Health Sciences Subject Guide

Learn about key library resources for studying health sciences

What is Boolean? How to make your searching easier

A normal keyword search might be ok for quick and general search but you may find too many results to scroll through. Many of the results will be irrelevant too.

When searching it helps to know what you're looking for, what you're not looking for and having the skills to find it. Using Boolean terms can help. Boolean Search uses a combination of keywords  to organise and sift through your searches. 

Using Boolean techniques when searching can:

  • Save time
  • Give more accurate and relevant search results
  • You can develop a broad or narrow search terms
  • Helps you navigate through appropriate research and disregard unrelated research
  • You can apply as many Boolean terms in the same search

Use any or a combination of the techniques below to make searching easier for you.

Boolean techniques


Using AND between keywords narrows your search results from just a keyword search

Covid-19 vaccine basic keyword search
Covid-19 AND vaccine will combine terms together and reduce result numbers
Covid-19 AND vaccine AND health promotion can be used more than once in same search



Using OR extends your search out which retrieves more results. Works very well with very similar keywords and means you're not missing out on any relevant research.

Covid-19 OR Coronavirus will search for same term simultaneously, giving more results
Covid-19 OR Coronavirus OR pandemic can be used more than once in same search



Use NOT to exclude results that you're interested in and reduce the number of records retrieved.

Covid-19 OR Coronavirus NOT SARS will exclude SARS records from search


Phrase searching works really well on all databases. Works well for a phrase that can also work as separate keywords.

Vaccine hesitancy will search for vaccine and hesitancy as separate words extending your search out and showing many irrelevant records with records with vaccine and records with the word hesitancy.
"Vaccine hesitancy" will retrieve records with phrase only
Covid-19 AND "Vaccine hesitancy" AND "health promotion" can be combined with other search terms


Truncation can extend your search out to ensure you're not missing out on any relevant records. Works with words with different endings. Go to last letter of word before ending changes and add *. Here's some examples:

nurs* will retrieve records with the keywords nurse, nurses, nursing
dentist* will retrieve records with the keywords dentist, dentists, dentistry
manag* will retrieve records with the keywords manager, managers, management
vaccin* will retrieve records with the keywords vaccine, vaccines, vaccination, vaccinations


You can use parentheses/nesting to build a search with a combination of Boolean Operators by using (...). The search inside the (...) is always done first so this can affect your search results. 


(Coronavirus OR Covid-19 OR pandemic) AND vaccine  keeps synonyms together
(Coronavirus OR Covid-19 OR pandemic) AND (vaccin* OR immun*) can be added more than once to each search
((Coronavirus OR Covid-19 OR pandemic NOT SARS) AND vaccine 

You can also use parentheses within parentheses. 

Some databases allow for searching for words within the same sentence or within a defined number of words within one another e.g.

SAME Covid-19 SAME "vaccine hesitancy" using SAME will search for Covid-19 and "vaccine hesitancy" in same sentence
W- Covid-19 W3 "vaccine hesitancy" using W3 will search for covid-19 within 3 words of "vaccine hesitancy" (change the number for limit of words between phrases/keywords e.g. W5, W7.)
NEAR Covid-19 NEAR  "vaccine hesitancy"  using NEAR will search for covid-19 within the databases definition of NEAR to "vaccine hesitancy"