Two of the most important aspects of a comprehensive literature search are to:

1. plan before searching, and
2.  make the search reproducible.

You make your search comprehensive by thinking through what you need to know and planning which databases and search terms you need to use to get your answer. You make the search reproducible by carefully documenting all the databases and search terms you used, whether you altered the search at all or decided to exclude certain items, and the items collected.

Below are recommended databases and links to articles that describe the process of doing a comprehensive literature search.

Six Steps to Smart Searching

Identify the keywords in your research question.

Keywords are words that carry content and meaning. The keywords in the research  question "What is the feeding range of the blue whale in the Pacific Ocean?" are feeding range, blue whale and Pacific Ocean.

Brainstorm synonyms for your keywords.

Think of words similar to your keywords in case a database doesn't use your original keywords. Synonyms for blue whale are baleen whale and Balaenoptera musculus.

Create Boolean searches using the keywords.

A Boolean search is a search using the words AND, OR and NOT between the keywords. These words have a special function when used in a database.

• The search [blue whale AND Pacific Ocean] will find all of the articles that contain both words. AND makes your search narrower.
• The search [blue whale OR Balaenoptera musculus] will find all articles that contain one word, or the other, or both. OR is placed between synonyms and makes your search broader.
• The search [blue whale NOT Atlantic Ocean] will find all articles containing "blue whale" and exclude the articles that also contain "Atlantic Ocean." NOT excludes articles that you don't want.  

Use the truncation symbol (or wildcard symbol) to search for word variations.

You can avoid doing multiple searches for variations on word endings using the truncation symbol * (the asterisk) in most databases.  Entering the keyword "blue whale*" will look for both blue whale and blue whales.

Add keywords to limit the type of article you retrieve.

If you want a literature review, add "AND review" to your keywords. To find a research study, add "AND study" to your keywords.

Enter your Boolean searches in the Advanced Search of a database.

Always go to the Advanced Search in a database to enter your Boolean searches because it gives you multiple boxes with the Boolean operators between them. If you are using a search with multiple search strings, enter OR within the search boxes and AND between the search boxes, e.g., [blue whale OR Balaenoptera musculus] AND [feeding range OR feeding grounds] AND [Pacific Ocean].

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Many instructors require you to use peer-reviewed sources for your papers and projects, but what does that mean?

• Peer review is the process of having experts in a field review the quality of an article or book before it is published
• Most articles in scholarly and academic journals are peer-reviewed
• Books published by university or academic presses are peer-reviewed

Most databases allow you to limit your search to peer-reviewed articles. Here are two examples:

When you don't know synonyms for your topic keywords, you can use science dictionaries and encyclopedias to find them. The UNT Libraries have numerous online reference books you can use.

Need help? Then use the library's Ask Us service. Get help from real people face-to-face, by phone, by email, or by live chat.