APA (7th ed.) Citation

Doyle, A. C., Smith, A. E., & Linton, A. (1961). The sign of four. Murray.

Chicago Style (17th ed.) Citation

Doyle, Arthur Conan, A. E. Smith, and Anne Linton. The Sign of Four. London: Murray, 1961.

MLA (9th ed.) Citation

Doyle, Arthur Conan, et al. The Sign of Four. Murray, 1961.

Warning: These citations may not always be 100% accurate.