Colton, J. (1968). Twentieth century. Time Life Books.
Lua i Stíl Chicago (17ú heag.)Colton, Joel. Twentieth Century. New York: Time Life Books, 1968.
Lua MLA (9ú heag.)Colton, Joel. Twentieth Century. Time Life Books, 1968.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.