APA (7th ed.) Citation

Koestler, A. (1959). The sleep walkers: A history of man's changing vision of the universe. Macmillan.

Chicago Style (17th ed.) Citation

Koestler, Arthur. The Sleep Walkers: A History of Man's Changing Vision of the Universe. New York: Macmillan, 1959.

MLA (9th ed.) Citation

Koestler, Arthur. The Sleep Walkers: A History of Man's Changing Vision of the Universe. Macmillan, 1959.