Sir C. F. Lascelles Wraxall, Historic Bye-Ways, Volume 2 (John Maxwell and Company, 1864), pp. 320-338.
John Elfreth Watkins, Famous Mysteries: Curious and Fantastic Riddles of Human Life that Have Never Been Solved (John C. Winston Company, 1919), pp. 120-126.
Jay Robert Nash, Among the Missing (Rowman & Littlefield, 1978), p. 331.
“The Curious Case of Orion Williamson,” Mystic Sciences, February 2018, https://mysticsciences.com/2018/02/01/the-curious-case-of-orion-williamson.
"Can Such Things Be?: The Riddle of Orion Williamson & the Strange Mystery of Ambrose Bierce,” Prairie Ghosts, https://www.prairieghosts.com/bierce.html.
Colin Wilson, Alien Dawn: An Investigation into the Contact Experience (Random House, 2012).
“Bierce’s Second Act,” Strange History, February 18, 2011, http://www.strangehistory.net/2011/02/18/bierces-second-act.