Caldwell, I. (2004). The rule of four. Dial Press.
Lua i Stíl Chicago (17ú heag.)Caldwell, Ian. The Rule of Four. New York: Dial Press, 2004.
Lua MLA (9ú heag.)Caldwell, Ian. The Rule of Four. Dial Press, 2004.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.