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EES1100 Master of Environmental Science Research Guide

This guide will help Master of Environmental Students at UTSC access key resources for research, learn about publishing and scholarly communication, prepare for internship, and more.

Build Your Search Using Boolean Logic

Boolean logic is the fancy language databases use to search. Boolean operators connect your keywords together.

The three basic boolean operators are: AND, OR, and NOT. 


("molecular pharming" OR "molecular farming" OR biopharm*) AND (plant* OR crop*) AND (vaccin* OR immuniz*)


AND links together distinct concepts in your topic. It tells the database that all the search terms must be present in the results.

  • Memory aid: AND does not expand - it's going to narrow your search results.

For example: cloning AND ethics AND humans would bring in results like the diagram below. 


OR links together related concepts or synonyms. This tells the database that any or all search terms can be present in the results.

  • Memory aid: OR is more - it's going to broaden your search results.

For example: you might be interested in "molecular pharming" OR "molecular farming" OR biopharming


NOT is used to exclude certain words or phrases from a search.

  • Note that using this operator runs the risk of excluding relevant results from your search - so use it sparingly!

For example: you might want to search for articles on children NOT adolescents.

Boolean Operators: AND, OR, NOT

*Created by McMaster Libraries

Improve Your Keyword Search

Try the following tricks to get the most out of your keyword searches:

" " Quotation marks tell the database to search two or more words as a phrase, i.e. side-by-side in that exact word order.

  • Example: "molecular pharming"

* Asterisks are used for truncation, which tells the database to search for any variant word endings on a term.

  • Example: vaccin* will retrieve vaccine(s), vaccination(s), vaccinate, vaccinating, etc.

? Wildcards are used to replace 0-1 characters within a word and are useful for catching spelling variations.

  • Example: wom?n retrieves both woman and women, colo?r retrieves both color and colour

Note that different databases may use different symbols for these functions, so it's important to always check the requirements for your specific database. If you need help, you can contact the library for assistance.

Boolean Modifiers "", *, ()