APA (7e ed.) Bronvermelding

Koestler, A., & Butterfield, H. (1964). The Sleepwalkers: A history of man's changing vision of the universe; with an introduction by Herbert Butterfield. Penguin.

Chicago (17e ed.) Bronvermelding

Koestler, Arthur, en Herbert Butterfield. The Sleepwalkers: A History of Man's Changing Vision of the Universe; with an Introduction by Herbert Butterfield. London: Penguin, 1964.

MLA (9e ed.) Bronvermelding

Koestler, Arthur, en Herbert Butterfield. The Sleepwalkers: A History of Man's Changing Vision of the Universe; with an Introduction by Herbert Butterfield. Penguin, 1964.