If you know the regulatory code section:
Code of Federal Regulations located in the library reserve range 63, or online on the Government Printing Office site’s Code of Federal Regulations page.
Standard Federal Tax Reporter KF 6365.C66, online CCH Intelliconnect (click “+” to see topics and code sections.)
This service is arranged by Internal Revenue Code (IRC) section. The full text of the relevant regulatory code follows the text of each code section.