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Boolean Operators

Boolean operators are used to define logical relationships between search terms. There are three Boolean operators: AND, OR, NOT.


AND retrieves results that include all of the search terms, which narrows your search. Example: abortion AND hawaii will find items that contain both "abortion" and "hawaii".


OR retrieves results that include at least one of the search terms, which broadens your search. Example: university OR college OR higher education will find items that contain either "university" or "college" or "higher education".


NOT enables you to exclude search terms. Example: therapy NOT physical will display items that mentioned therapy but had no mention of "physical".


Be sure to CAPITALIZE your boolean operator. A good rule of thumb is to enclose your OR searches with parentheses. Examples:

  • (politics OR political) AND (media OR news OR mass communication)
  • ethics AND (assisted suicide OR euthanasia)

Truncation & Wildcards

Truncation and wildcard symbols vary by database. Check the help screen of each database to find out which symbols they use.

Common symbols are *, !, ?, + or #


This technique enables you to broaden your search by including variant word endings and spellings. When searching, place the truncation symbol at the end of the root word.


  • child* = child, childs, children, childrens, childhood
  • theat* = theater, theaters, theatre, theatres, theatrical


Wildcards allow you to substitute a symbol for one letter of a word.


  • favo!r = favor, favour
  • wom?n = woman, women


Phrase Searching is searching for two or more words as an exact phrase. This means that results must contain an instance of the words in its exact order. Databases will typically search for a string of words using the AND as a connector (global warming causes = global AND warming AND causes), but this will also yield items that contain information about global and warming but not "global warming".

Most databases will allow you to search for phrases. You can typically do this by using (parentheses) or "quotes" around the words, but some databases also have a special search box or button to allow for this. Check the help screen of each database to be sure

Example: *Note the difference in the amount of results and the highlighted search terms in the result list

pulmonary heart disease

"pulmonary heart disease"

Search Fields

Library databases contain items that have its own record. These are called either item records or bibliographic records. Each record has searchable fields. Common fields include:

  • author
  • title
  • journal title
  • abstract
  • publisher
  • date/year of publication
  • subject/descriptor

Using these fields when searching yields more relevant results. When on the search page, look for drop down boxes or menus, then select the field you want to search.

Example: You're looking for books written BY Edgar Allen Poe. If you do a keyword search or don't specify a field, you'll get books written by or about him. That'd be a lot of item records to look through! However, if you search for his name in the Author field, you'll only receive results for books that he authored.

SEARCHING - Keyword vs. Subject

Keyword searching

This is how you typically search for things online. You think of key/important words or phrases, then type them in to execute your search. This is a great way to start your search.

Easy to use in a search, as it utilizes "natural language" The database is searching for your keywords throughout the entire item record, so the keywords may not necessarily be connected together.
Flexible - you can easily combine multiple search terms together May yield too many or too little results
  May yield too many irrelevant results.

Subject searching

When you do a Subject search, you are utilizing Subject Headings, which are how the database describes/groups/organizes each item. Databases may identify these differently, as "Subject", "Subject Terms", or "Subject Headings".

The most precise way to search in a database - results are VERY relevant. Not flexible or easy to guess. You need to know the precise "controlled vocabulary" term/phrase.
Best Way to Search

1. Start with a keyword search

2. Find a few relevant results that are close to what you're looking for.

3. Look at the "Subject" field and note ones that are relevant to your topic.

4. Do a second search, utilizing the controlled vocabulary you noted. Be sure to change the search field to reflect the search you're doing (Subject).