Al Gore's testimony before the U.S. House of Representatives Energy and Commerce Committee's Subcommittee, and the Science and Technology Committee's Subcommittee on Climate Crisis, abcnews.go.com. March 21, 2007.
William J. Clinton “Public Papers of the Presidents of the United States, William J. Clinton, 1993, Bk. 2, August 1 to December 31, 1993”, Government Printing Office