CFR - Code of Federal Regulations (Nexis Uni) (1981+)
"The CFR - Code of Federal Regulations file contains the full text of all titles from the Code of Federal Regulations (CFR). The CFR is a codification of the general and permanent rules and regulations published originally in the Federal Register by executive departments and agencies of the federal government. CFR archives are available from 1981. On Lexis Advance, if an archived version of a CFR section is available, then a link will appear under About This Document, followed by the number of archived versions in parentheses. "