APA (7th ed.) Citation

Maugham, W. S. (1920). The unknown: A play in three acts. W. Heinemann.

Chicago Style (17th ed.) Citation

Maugham, W. Somerset. The Unknown: A Play in Three Acts. London: W. Heinemann, 1920.

MLA (9th ed.) Citation

Maugham, W. Somerset. The Unknown: A Play in Three Acts. W. Heinemann, 1920.