About the CFR
The Code of Federal Regulations is the codification of the general and permanent rules published in the Federal Register by the executive departments and agencies of the Federal Government.
e-CFR
The e-CFR, as noted on the website, is "a currently updated version" of the Code of Federal Regulations (CFR). It is NOT an "official legal edition" of the CFR.
CFR on GovInfo
GovInfo provides access to the CFR (1996-2020). Govinfo also provides access to Finding Aids, including the CFR Index, which can be useful in locating the applicable regulations.