Once you have found some relevant or important articles on your topic, one way to expand your search is through citation searching.  Citation searching looks for all of the articles or books that have cited your initial paper since it was written.  There are two main databases you can use for this kind of search:  Web of Science and Google Scholar.  Both of these databases cover somewhat different sources, so it can be helpful to try both.

Web of Science (Tip - make sure you choose the Cited Reference Search option):

Search by the first author's name. Web of Science is picky - enter the last name first and then the first initial(s) without a period.

Find the entry that matches the article you had in mind. Especially look at the Cited Work and Year Column. Select that entry, then choose Finish Search.

Google Scholar (Tip - click on the cited by link to see all of the citing papers):

Most databases allow you to narrow your search to certain kinds of articles - like review articles. Look for narrowing options (called facets) on the side of your search results page.

This example is from a Web of Science search. After searching for my keywords, I looked on the left-hand side of the page to refine my results by review articles. This lets me see articles that provide a broader summary of the research on my topic.

Most of us start a search with key words that we want to explore.  Some additional search approaches are to:

• Begin by reading review articles, which are articles published in peer reviewed journals. Review articles synthesize and summarize the work of a particular sub-field, rather than report on new results. They can provide helpful background information. Read about how to find review articles in the database Web of Science, or simply try adding "review" as a keyword to your topic search. For example, captive breeding zoos review. See this article on pangolins for an example of a review article.
• Search by the author of an important paper you find
• Use the references from a useful book chapter or article
• Use citation searching to find out who has cited a relevant article
• Use the controlled vocabulary (also called subjects terms or categories) as illustrated in this picture to learn more precise vocabulary and narrow down your search

Tip - 1. Enter short keywords.  Click Search.  2. Look for options to narrow your search results using controlled vocabulary or subject terms on the left-hand side of the results page.

Here are some tricks of the trade to make your searches more effective (these work in most databases):

• Use quotes to search for an exact phrase or name
• Use an asterisk with word roots to expand beyond an exact word

Searching in Google? Try these tricks:

• Search for a specific file type - filetype:pdf
• Search within a particular website - site:nytimes.com
• Look for related words with a ~

From: Hack College, Get More Out of Google