APA (7th ed.) Citation
Doyle, A. C. (1994). The sign of four. Quality Paperback Book Club.
Chicago Style (17th ed.) Citation
Doyle, Arthur Conan. The Sign of Four. New York: Quality Paperback Book Club, 1994.
MLA (9th ed.) Citation
Doyle, Arthur Conan. The Sign of Four. Quality Paperback Book Club, 1994.
Warning: These citations may not always be 100% accurate.