APA (7th ed.) Citation

Heather, N., & Robertson, I. (1985). Problem drinking. Penguin books.

Chicago Style (17th ed.) Citation

Heather, Nick, and Ian Robertson. Problem Drinking. Harmondsworth: Penguin books, 1985.

MLA (8th ed.) Citation

Heather, Nick, and Ian Robertson. Problem Drinking. Penguin books, 1985.