Using Boolean operators (AND, OR and NOT) to combine your keywords is a way of making your search smarter and more targeted. Consult the database help screens for additional information and tips.
When you use the operator AND you will narrow your search and get fewer results
When you use the operator OR you will broaden your search and get more results. You often use OR for synonyms or similar concepts.
When you use the operator NOT you exclude certain words from your search query.
"household waste" AND (biogas* OR biofuel*) NOT fertilizers
This search query will retrieve documents with the term household waste and any of the other two words but not the word fertilizers.
The film below is made by Gumberg Library at Duquesne University, Pittsburgh.
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Note! Some databases truncate your words automatically.
Databases like Compendex and Web of Science are constructed by entering data in different fields. There are author, title, year and abstract fields (and many more). You can use these fields for limiting your search.
When searching for Colin Poole you can choose the author field for finding articles by Poole himself, the abstract field for finding articles mentioning him or the title field for finding articles where he is a prominent figure.
Using a thesaurus can be of great help when you want to conduct subject searches. A thesaurus presents words grouped together according to similarity of meaning, for instance containing synonyms and sometimes also antonyms. In a database it can guide you to the controlled vocabulary of subject headings and you will know which synonym to use when searching, and also get suggestions for other search words that are more narrow or more general.
The Thesaurus function helps you by: