Impeachment, Investigation, and Contempt Precedents (from Hinds’s, Cannon’s, and Deschler’s Precedents of the House of Representatives Download
The Impeachment Process in the House of Representatives (Congressional Research Service, 2019) Download
Legal Information Institute, material on impeachment
Legal Information Institute, material on Congressional investigations
The Founders’ Constitution, Documents on impeachment
Transcripts of witness testimony before the House Intelligence Committee