George Henry Lewes (1864). “Aristotle: a chapter from the history of science including analyses of Aristotle's scientific writings”, p.86, London : Smith, Elder and Company
Letter to "Weird Tales" editor Edwin Baird, printed in "Weird Tales" 3, no. 3 (March 1924); Quoted in "Lord of a Visible World: An Autobiography in Letters" edited by S. T. Joshi, (p. 122), 2000.
"John F. Nash Jr. - Biographical". "Les Prix Nobel" ("The Nobel Prizes 1994") edited by Tore Frängsmyr, Nobel Foundation, Stockholm, www.nobelprize.org. 1995.