"A paper commonly used in various courts—such as a probate, matrimonial, or traffic court—that is served upon an individual to notify him or her that he or she is required to appear at a specific time and place.
Reference to a legal authority—such as a case, constitution, or treatise—where particular information may be found.
Cases are published in a series of books called reporters, which are compilations of judicial decisions made in a certain court, state, or jurisdiction. Reporters are published in consecutively numbered volumes, each of which contains the most recently decided cases. When the volume numbers on a set of reporters get too high, the publisher will begin a new set with a new series of numbers.
To refer to a particular case in a reporter, a designation including the volume number, the name of the reporter, and the page number is given. If, for example, a case decided in the U.S. Supreme Court were cited as 60 S. Ct. 710, the case would be in volume 60 of the Supreme Court Reporter on page 710. To promote uniformity of citations, many lawyers and law students use The Blue Book: A Uniform System of Citation, commonly referred to simply as The Blue Book. This manual is published jointly by law schools at Harvard, Yale, Columbia, and the University of Pennsylvania. Other citation manuals have also been published."
Text: "Citation." Gale Encyclopedia of American Law, edited by Donna Batten, 3rd ed., vol. 2, Gale, 2010, pp. 398-399. Opposing Viewpoints In Context, http://link.galegroup.com/apps/doc/CX1337700836/OVIC?u=lom_stclaircocc&sid=OVIC&xid=699f5e46. Accessed 23 May 2018.
For specific examples on how to cite, consult The Bluebook.
This library research guide from Georgetown University Law Library is also helpful in explaining legal citations. Below is an example of a basic legal citation from this guide.
Image from : "Basic Case Citation." Georgetown University Law Library, guides.ll.georgetown.edu/bluebook/citing-cases. (current as of 2/14/19)