Rights and Access
The vast majority of the U.S. Congressional Serial Set is a work of the U.S. Government not subject to copyright in the United States and free to use or reuse. However, where the U.S. Congressional Serial Set reprints copyrighted material (for example, published in the United States less than 95 years ago, or unpublished and the author died less than 70 years ago), copyright protections may apply. For those instances, you’ll need to assess the risks of using the material for the purposes you intend.
More about Copyright and other Restrictions.
For guidance about compiling full citations consult Citing Primary Sources.