Catalog of U.S. Government Publications
Basic finding tool for publications from a wide range of agencies.
Developing (2010- ) gateway to official U.S. Federal Government publications.
Internet search engines limited to government Web pages. (Keep in mind the impermanance of Web information. For example, what about presidential documents?)
Federal Government Watchdog Agencies
Congressional Research Service, Congressional Budget Office, etc.
Access to nearly every document created by Congress, including committee hearings.