APA (7th ed.) Citation

Charles, E., & Dickens, C. (1908). Keys to the Drood mystery. Collier.

Chicago Style (17th ed.) Citation

Charles, Edwin, and Charles Dickens. Keys to the Drood Mystery. London: Collier, 1908.

MLA (9th ed.) Citation

Charles, Edwin, and Charles Dickens. Keys to the Drood Mystery. Collier, 1908.