Alexander Hamilton, James Madison, John Jay (2016). “The Federalist Papers and the Constitution of the United States: The Principles of the American Government”, p.140, Skyhorse Publishing, Inc.
United States. President (1981-1989 : Reagan), United States. President (1981-1989 : Reagan)., Ronald Reagan, United States. Office of the Federal Register (1982). “Ronald Reagan”
Attributed in Reader's Digest, Sept. 1937. The attribution to Twain is obviously spurious because Twain's father died when the future writer was eleven years old.