Committee Prints contain the work done by a congressional committe in the process of passing a law or conducting an investigation. They can be a treasure trove of information including research, memos, CRS Reports, etc. However, since a committee decides what it wants to publish in a Print, the amount of information can vary from Print to Print [Numbers in brackets denote Congressional session].
Indexing and full-text access for publications of the United States Congress such as hearings, committee reports and prints, CRS reports, as well as executive branch documents. (Congressional Publications) [dates vary]
One stop shopping for all U.S. congressional publications. Provides indexing and abstracts of congressional publications back to 1789, including the full-text of published Congressional Hearings (1824-present; unpublished hearings until 1979), Committee Prints (1817-present), Congressional Research Service (CRS) Reports (1916-present), Congressional Record and its predecessor titles (1789-present), U.S. Congressional Serial Set and Maps (1789-present), Executive Branch Documents (1789-1932), Presidential Executive Orders and Presidential Proclamations (1789-present), and Legislative Histories (1969-Present; earlier legislative histories are available via ProQuest's Legislative Insight).
[dates varies] Govinfo.gov (click on the committee name to see their publications)