When lawyers present legal arguments and judges write opinions, they cite authority. They support their representations of what the law is and how it applies to a given situation with references to statutes, regulations, and prior appellate decisions they believe to be pertinent and supporting. They also refer to persuasive secondary literature such as journal articles. As a consequence, those who read and do law writing must master a new, technical language – "legal citation." Known by the color of its cover, The Bluebook was the codification of professional norms that introduced generations of law students to "legal citation."
Introduction to Basic Legal Citation (online ed. 2012: http://www.law.cornell.edu/citation/) by Peter W. Martin
Cornell University Law School provides example citations for formatting legal citations:
§ 2-210. Case Citations – Most Common Form
§ 2-200. How to Cite Judicial Opinions
§ 2-300. How to Cite Constitutions, Statutes, and Similar Materials
§ 2-400. How to Cite Regulations, Other Agency and Executive Material
§ 2-800. How to Cite Articles and Other Law Journal Writing
§ 7-500. Table of State-Specific Citation Norms and Practices (Search for Wisconsin)
Specific Formatting Citation Questions
§ 5-000. UNDERLINING AND ITALICS
Introduction to Basic Legal Citation (online ed. 2017 https://www.law.cornell.edu/citation/ by Peter W. Martin)