APA (7th ed.) Citation

Letts, B., Leopold, G., & Willow, A. (1974). Doctor Who and the Daemons ... Target Books.

Chicago Style (17th ed.) Citation

Letts, Barry, Guy Leopold, and Alan Willow. Doctor Who and the Daemons ... London: Target Books, 1974.

MLA (9th ed.) Citation

Letts, Barry, et al. Doctor Who and the Daemons ... Target Books, 1974.