A "citation" is a reference to one publication. It is often referred to as a "reference." References are listed in a A Bibliography, or Literature Cited, or References section of a paper.
Ask yourself the following questions:
Do you have a citation, and just need to find the article online?
Use the Finding Full Text Guide Research Guide
Do you have a citation and want to find other publications that list your citation in the bibliography?
Keep reading; you want to do a "Cited Reference Search"
Citated Reference Searching Defined
This 3 minute video, from the University of Alberta Library does a nice job illustrating the concept of Citation Searching.
Citation Reference Searching--What Is It?
"Citation Searching", or "Cited Reference Searching" is a method of identifying related articles. You begin with a known citation and by doing a "cited reference" search, find articles (written after the article you know about) which include your article in the reference list. Essentially, you are moving forward in time, beginning with a known article and finding newer articles which use the older, known article as one of the references in the newer article's bibliography.
This method complements searching for articles by keywords, and the results you get will vary depending upon the currency and importance of the known citation. If your citation is only one or two years old, it may be too recent to have been cited by others. Results will also vary depending upon the database in which you are doing the Cited Reference Searching.
Go to the "Cited Reference Databases" tab at the top of the screen to continue.