Use the index volume of the CFR, labeled "CFR Index and Finding Aids." The "Parallel Table of Authorities and Rules" gives the following cross-references:
United States Code (USC) to CFR
Statutes at Large (Stat.) to CFR
Public Law (PL) to CFR
Presidential Documents to CFR
In the table of contents to the subparts of each CFR title you will find the following citations:
Authority: Gives Statutes at Large, United States Code, and Public Law citations for enabling legislation.
Source: Federal Register volume, page and date.
Each rule and proposed rule in the Federal Register gives CFR citation.
CFR sections will give a reference to the Federal Register.