APA (7th ed.) Citation

Doyle, A. C. (1992). The sign of four: Intermediate level. Heinemann.

Chicago Style (17th ed.) Citation

Doyle, Arthur Conan. The Sign of Four: Intermediate Level. Oxford: Heinemann, 1992.

MLA (9th ed.) Citation

Doyle, Arthur Conan. The Sign of Four: Intermediate Level. Heinemann, 1992.