Letter of Archibald Butt to Clara F. Butt on June 01, 1909. "Taft and Roosevelt: The intimate letters of Archie Butt" by Archibald Willingham Butt, 1930.
Theodore Roosevelt (2015). “Theodore Roosevelt on Bravery: Lessons from the Most Courageous Leader of the Twentieth Century”, p.4, Skyhorse Publishing, Inc.
James Monroe, Daniel Preston, Marlena C. DeLong (2003). “The Papers of James Monroe: A documentary history of the presidential tours of James Monroe, 1817, 1818, 1819”, Greenwood Pub Group