President Clinton was impeached on December 19, 1998.
From our government documents collection: Impeachment inquiry : William Jefferson Clinton, President of the United States : presentations by investigative counsel: impeachment inquiry pursuant to H. Res. 581: Presentations by investigative counsel, Washington : U.S. G.P.O. (1999)
From the Library of Congress: The impeachment and trial of President Clinton : the official transcripts
