Nikola Tesla (2002). “Nikola Tesla on His Work with Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power: An Extended Interview”, p.110, 21st Century Books
John Esten Cooke, Robert E. Lee (2017). “General Robert E. Lee: The True Story of the Infamous “Marble Man”: The Life & Legacy of Robert E. Lee, Including & Personal Writings, Speeches and Orders”, p.42, Madison & Adams