U.S. Supreme court decisions are published in the title U.S. Reports, the Court of Appeals in the Federal Reporter, and the District Courts in the Federal Supplement. Examples of citations follow the format below. The format is title of case, volume, publication title, page, and date in parentheses.
U.S. Federal
Supreme Court: Citizens United v. FEC, 558 U.S. 310 (2010).
U.S. Court of Appeals Perfect 10 Inc. v. Amazon.com Inc., 487 F.3d 701 (2007)
District Court Van Stelton v. Van Stelton, 904 F. Supp. 2d 965 (2012)
California court decisions for the Supreme Court, the Court of Appeals, and Superior Courts are published in a variety titles. A case decision in a database such as LEXIS/NEXIS will provide all the sources. For example, in People v Williams, it is published in 28 Cal. 4th 408; 49 P.3d 203; 121 Cal. Rptr. 2d 854; 2002 Cal. LEXIS 4360. The most common source is the California Reporter.
California
The People v. Steven Vaughn Williams, 121 Cal. Rptr. 2d 854 (2002)