ENGR 471: Keyword Searching

All of the databases and search engines discussed on this guide will respond best to keyword searches using Boolean operators. Things to keep in mind when choosing keywords:

1.  Keywords represent the essential concepts of a topic or research question.
   Example - "A mechanism or method of reducing emissions in two-stroke engines" can be cut down to this list of keywords:
   • reduce
   • emissions
   • two-stroke
   • engine
2.  Be sure to brainstorm relevant synonyms and related (broader or narrower) terms. It's not necessary to include every synonym or related term in your search; but not all authors are going refer to concepts by the same terms, so it's always helpful to have a few keyword options if your searches are coming up empty.
   Example
   • reduce, minimize, decrease
   • emissions, carbon monoxide, hydrocarbons
   • two-stroke, two-cycle, internal combustion

There are three Boolean operators in database searching: AND, OR, and NOT. These operators form relationships between words and establish parameters by which database search engines populate results.

AND

Combining terms with AND directs a search engine to provide you with all results that contain all words connected with AND. So, for example, a search for:

two-stroke AND emissions AND reduction

will only return articles that mention all three keywords.

In general, use AND to connect all of the key concepts in a research question or topic.

OR

Combining terms with OR directs a search engine to provide results that contain at least one of the terms provided. For example, a search for:

two-stroke OR two-cycle OR internal combustion

will return articles that mention one, two, or all of these terms.

In general, use OR to connect synonyms and related terms.

NOT

NOT directs a database to exclude any results that mention a certain term. For example, a search for:

two-stroke NOT four-stroke

would eliminate any resources that mentioned "four-stroke" engines.