APA (7th ed.) Citation

Ponting, C. (1991). A green history of the world. Penguin Group.

Chicago Style (17th ed.) Citation

Ponting, Clive. A Green History of the World. New York: Penguin Group, 1991.

MLA (9th ed.) Citation

Ponting, Clive. A Green History of the World. Penguin Group, 1991.