The Code of Federal Regulations (CFR) is compilation of federal regulations currently in force that are organized by topic. Remember, just as with federal statutes, not all federal regulations are codified. Additionally, some federal agencies promulgate regulations via other means. The CFR is no longer updated in print as there is an electronic version available on the GPO's website. Also, note that federal regulations are not annotated in the same way as the statutory code. They will not contain references to secondary materials. You may, however, use West's KeyCite or Lexis' Shepard's to locate materials which discuss or analyze a particular regulatory code section. Finally, the history of each regulation code section is located at the bottom of the entry and refers to the Federal Register (Fed. Reg.) which is where federal rules are proposed and notices of adoptions are published.