↑Falco, Charles M.; Guggenheim Museum Staff (1998), «Issues in the Evolution of the Motorcycle», in: Krens, Thomas; Drutt, Matthew, The Art of the Motorcycle, ISBN0892072075, Harry N. Abrams, pp. 24–31, 98–101
↑Kerr, Glynn (agosto de 2008), «Design; The Conspiracy Theory», Irvine, California: Aviation News Corp, Motorcycle Consumer News, ISSN1073-9408, vol. 39 no. 8, p. 36–37
↑Brown, Roland; McDiarmid, Mac (2000), The Ultimate Motorcycle Encyclopedia: Harley-Davidson, Ducati, Triumph, Honda, Kawasaki and All the Great Marques, ISBN1840388986, Anness Publishing, p. 12