The United States Congressional Serial Set is the official collection of reports, hearings, and other documents requested by or generated by Congress.
These materials may be in microformat or in bound volumes, depending on the year.
For each document, you need to know: the title of the document, the publications series and number, the Congress and session, and the serial volume number.
Use the CIS U.S. Serial Set Index (Government Documents Reference - 2nd Level North - Z1223.Z9 C65 1975) to get this information. The Serial Set is arranged first by Congress, then alphabetically by subject/keywords. Each entry will contain the information you need to locate the document.
Also of interest - Guide to American Indian Documents in the Congressional Serial Set, 1817-1899.
Congressional Record [catalog record]
The Congressional Record contains the text for debates and statements from the floor.
Monthly Catalog of U.S. Government Publications (Government Docs Reference - 2nd Level North - Z1223. A18)
Indexes all government publications published by the Government Printing Office. One of the few places to locate information regarding Congressional hearings.