Rule 11 of the Bluebook presents the citation methods of the U.S. federal constitution.
Example: art. 1, § 9, cl. 9, U.S. Const. amend. XIV, § 2.
Rule 14 of the Bluebook covers the citation methods for the Code of Federal Regulations (C.F.R.).
[Title Number] C.F.R. [§ Section Number] (Date).
Example: 36 C.F.R. § 2.15 (2017).