When you search for scholarly or peer-reviewed articles in library databases, you must select keywords with care. 

You use keywords all the time searching on the web via Google or your search engine of choice. Each word you plug in a search box is a keyword, but they don't work quite the same in library databases as with Google. Typing a question or phrase describing a topic into a library database will likely give zero or very few results. Why?

Databases don't understand natural language and will only return results containing all of the words you put the search box.

For this reason, you need to break your topic down into concepts or specific keywords that are most important to the search. Take a look at this topic:

The key elements of this research question are: capital punishment, deterrent effect (or just deterrence) and homicides. The causal relationship is already implied by searching for the keywords together, thus have, a and on are not necessary as keywords.

Knowing the most important elements of your topic, the next step is brainstorming out potential keywords: related words, broader and more specific words, and synonyms – words that mean the same thing.

Synonyms are especially important because the words other people use may not be the same ones you naturally think of. Library database searches depend on what words the author used and what words are assigned to articles by the indexers, called subjects or subject headings. 

Let’s brainstorm out our topic. Keywords Include:

• capital punishment - death penalty
• deterrent effect - deterrence, crime prevention
• homicide - murder, capital crimes

Read up on the topic in encyclopedias or on reputable websites.

Often it just takes a bit of time reading general overviews of a topic to identify recurring keywords, people, and the like.

Run a basic search in a library database appropriate for you topic.

Doing a simple search with a broad keyword or two will give you a good idea of what's available. Once you have some results:

• Read short articles for general information.
• Look for articles with strong bibliographies--a great place to start exploring.
• Take a look at the subjects being generated from your keywords. Anything useful?