Gaya APA
Koestler, A. (1964).
The Sleepwalkers a history of man`s changing visim of the universe .
Harmondsworth:
Penguin Books.
Gaya MLA
Koestler, Arthur.
"The Sleepwalkers a history of man`s changing visim of the universe".
Harmondsworth:
Penguin Books,
1964.
Buku.