Print Sources Available in the University Library
Mandatory standards are governmental in origin, though they may have been adopted from one or more voluntary standards.
Many government agencies issue standards as regulations or separate publications. Finding these is hard. Standards issued as regulations are published in the Federal Register and the Code of Federal Regulations (CFR).
Calling the local office of the agency or searching the Monthly Catalog of United States Government Publications, available on the Internet via the Catalog of U.S. Government Publications may be productive. Search for STANDARDS.