APA (7th ed.) Zitazioa
Doyle, A. C. (1994). The sign of four. Quality Paperback Book Club.
Chicago Style (17th ed.) Zitazioa
Doyle, Arthur Conan. The Sign of Four. New York: Quality Paperback Book Club, 1994.
MLA (9th ed.) Zitazioa
Doyle, Arthur Conan. The Sign of Four. Quality Paperback Book Club, 1994.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.