The United States Code (U.S.C.) is the codification by subject matter of the general and permanent laws of the United States. It is divided by broad subjects into 53 titles. It was first published in 1926. The U.S.C. is the official code of the United States, and is published (in print) every six years with annual cumulative supplements. It is also available online at Govinfo.gov.
It is recommended that you use an annotated version of the U.S.C., which include explanatory text and links to secondary and primary law (including case law.) Annotated versions include U.S.C.A. (Westlaw) and U.S.C.S. (Lexis).
From the Georgetown Bluebook Guide.
The basic format of a statutory citation is as follows:
Rule 12 in the Bluebook governs how to cite statutes and provides extensive instructions on how to format statutory citations, and also provides guidance on citing municipal ordinances, rules of evidence and procedure, and uniform and model laws. In addition, you will need to consult Table 1 in order to format a citation to a statute. Table 1 provides a list of statutory codes and abbreviations for federal statutes and state statutes as well as the preferred statutory code to cite for federal statutes and each state's statutes.
More information about Bluebook Citations for Federal Statutes can be found at the Georgetown Law Library's Bluebook Guide.