Cita APA (7a ed.)

Koestler, A. (1964). The sleepwalkers: A history of man's changing vision of the universe. Penguin.

Cita Chicago Style (17a ed.)

Koestler, Arthur. The Sleepwalkers: A History of Man's Changing Vision of the Universe. Harmondsworth [etc.]: Penguin, 1964.

Cita MLA (9a ed.)

Koestler, Arthur. The Sleepwalkers: A History of Man's Changing Vision of the Universe. Penguin, 1964.