Boolean operators are small words (AND, OR, NOT) that can give you more control over your search results. These three words used with your keywords can help narrow, broaden, and focus your results.
Narrowing your search: if you're getting too many results, or results that are too general
AND: By adding AND to your keywords, results will include both key terms. The more you include AND, the fewer results you'll have.
Example: If your research question is, How does the amount of rain affect deforestation in Brazil? you could search "rainfall AND deforestation AND Brazil."
NOT: The Boolean operator NOT will also limit the results returned. It should be used sparingly.
Example: If your research question is exploring the effects of pollutants on Mexico but your results keep coming back with results on Mexico City, your search will look like pollutants AND Mexico NOT city.
Broadening your search: if you're not getting enough results
OR: Including OR into your search terms expands your search results -- casting a wider net for resources you want to see.
If your research question is Are teens who spend time on social media more depressed? pull out the key terms teens, social media, depressed. But maybe you're also wanting to see results that include synonyms. Your search may look like teens OR teenagers OR adolescent.
If you've tried a few different Boolean terms and you're still not getting relevant results, you may want to consider switching databases (see how under the "Getting Started" tab in this guide) or Using Google Scholar (below).
Sometimes you end up with more search results than you could possibly read. You'll want to refine your results to give you the best, most relevant articles. You can do this by refining by:
subject (what an article is primarily "about." Searching by subject or refining your search by subject means your results will be more directly related to that search term.)
publication date (when the article came out)
source type (e.g., books, articles, trade publications, newspapers. See the "Understanding Your Results" tab in this guide for definitions of each different source type)
Subject headings are terms that a database uses to keep descriptions consistent. Sometimes these headings are not necessarily the first terms that come to mind when starting your research. Headings could be discipline specific and include specialized language.
On an academic article, you might see a section labeled Subject Terms, or MeSH (Medical Subject Headings) terms, or Author-Supplied Keywords. Any of these can be helpful; these are terms that either the database supplied, the medical field uses, or the author provided. By clicking on the given terms, you'll be taken to a new search specific to that term. This will produce more results which can help you get to the best sources for your research.
You can also use the dropdown field to search by subject term, instead of by keyword.
A particularly useful research tool is Google Scholar. Google Scholar is especially helpful if you know the name of an article you'd like to find or if you have one very relevant article and you'd like to find more; just copy and paste the article name into the Google Scholar search bar.
From there you should see the original article (if available); you can also select Cited By to get a list of all other articles that have referenced this article or select Related Articles to find articles on similar topics. Articles can be accessed by clicking the links on the right.
A great way to find sources is to use the existing web of citations between academic sources, called backward and forward citing.
Backward citation means looking at the references page of a book or article and visiting the articles your source cites that are relevant to your topic. This is a great way of getting a handle on the scholarship surrounding a topic.
Forward citation means finding sources that cite the article you're currently reading. Google Scholar has an excellent tool to do this: just copy and paste the title into the search bar, then select the "cited by" link beneath the result. (See image above.) This will generate the articles that have cited this article in their references page.
You can find more details in the video below: