Legislation United States Statutes at Large contains the text of every piece of legislation that passes the Congress, is signed by the president, and becomes law. It has one or two fat volumes per year, and a pretty good subject index each year. Legislation on Foreign Relations through 1998 . Joint committee print, House Committee on International Relations and Senate Committee on Foreign Affairs, 1999. The on-line version is computer searchable, and thus easier to use than a paper copy would be.
Much interesting information is released by Congressional committees.
The transcripts of committee hearings are often published along with considerable amounts of documentation, or the documents may even be published without the excuse of a hearing. The Congressional Information Service has a process called Documents on Demand by which one can order either microfilm or paper copies of congressional committee hearings and other congressional documents, dating from the 1970s and after. Congressional Information Service, 1986. 9,072 microfiches, about 7,300 hearings. 89th Congress to 90th Congress, 1965-1968 .