Theodore Roosevelt (2012). “Compilation of the Messages and Papers of the Presidents Section 2 (of 2) of Supplemental Volume: Theodore Roosevelt, Supplement”, p.91, tredition
Theodore Roosevelt (2015). “Theodore Roosevelt on Bravery: Lessons from the Most Courageous Leader of the Twentieth Century”, p.36, Skyhorse Publishing, Inc.
Theodore Roosevelt (2015). “Theodore Roosevelt on Bravery: Lessons from the Most Courageous Leader of the Twentieth Century”, p.57, Skyhorse Publishing, Inc.