One of the issues with agency information being made available exclusively online is that information can get lost when the agency edits or redesigns its website. Fortunately, the Internet Archive has been archiving the web for years. The Internet Archive's Wayback Machine can retrieve older versions of websites, so that you maybe able to recover information that otherwise would be lost.
The United States Code is the codification by subject matter of the general and permanent laws of the United States. It is divided by broad subjects into 54 titles and published by the Office of the Law Revision Counsel of the U.S. House of Representatives.
The Code of Federal Regulations (C.F.R) is the codification of the general and permanent rules published in the Federal Register by the departments and agencies of the Federal Government. It is divided into 50 titles that represent broad areas subject to Federal regulation. The 50 subject matter titles contain one or more individual volumes, which are updated once each calendar year, on a staggered basis
The Federal Register (Fed. Reg.) is the official daily publication for rules, proposed rules, and notices of Federal agencies and organizations, as well as executive orders and other presidential documents.