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Gibson D. Lewis Library Libguides

Literature Searching

Need to find literature for your research, but don't know where to start? This guide is here to help!

Boolean Operators

Boolean operators are used to pull search terms together in a way the database can understand. Each operate communicates a different command. Below you can see how the Boolean operators AND, OR, and NOT are used.

AND

AND will narrow the search. It requires all terms connected by AND to be included in the search results. The example reflects a search that requires both dogs AND cats to be in the results.

OR

OR will expand the search. It allows for either term to be present in the search results. It is used for connecting synonyms of search topic key terms. The example reflects a search that requires either dogs OR cats to be included in the results. It does not require both.

NOT

NOT is used to exclude terms from the search. Use caution when using NOT, as it may weed out items are relevant to the topic. The example reflects a search that includes dogs but does not include any articles that also talk about cats.

Connecting Boolean Operators Together

Sometimes, when you have a complicated research question, using multiple Boolean Operators in one search string can be helpful. In these instances, connecting different parts of the search string together using parentheses will help (it will resemble a simple math equation). Let's connect the first two examples above:

Example: (diabetes AND nutrition) AND (medication OR prescription)

In this example, the system will first look for articles containing "diabetes AND nutrition." It will then look through the results for articles that contain "medication OR prescription." So, we will only get results that have to do with medication as it relates to the nutrition of diabetic patients.

If we did not use parentheses, our search string would look like this:

Incorrect Example: diabetes AND nutrition AND medication OR prescription

Do you see the difference? In the incorrect example, the system will look for articles that contain "diabetes AND nutrition AND medication," as well as ALL the entries in the database that contain "prescription," whether or not they have anything to do with the first part of the search.

 

Quotation Marks

There may be instances when searching which require results with a very specific term or phrase. When looking for an exact phrase or word, placing quotation marks on either side will prompt the database to search for the words in exactly the order they appear.

For example: "food desert"

By placing quotation marks on either side the database knows to look for those terms together, not separately in the article.

 

Database Filters

Most databases will have filtering options built in to the search page that can help narrow down your search results.  Options for filters can range from:

Date, Language, Age, Article Type, Location, etc.

Each database will present different options, but they can really help refine your search and make it more specific. (Think filtering by size or color when online shopping). Here is an example of filters in Web of Science, a popular database available on the Lewis Library web page: