APA (7th ed.) Citation

Keen, M. L. (1962). The how and why wonder book of prehistoric mammals. Wonder Books.

Chicago Style (17th ed.) Citation

Keen, Martin L. The How and Why Wonder Book of Prehistoric Mammals. New York: Wonder Books, 1962.

MLA (9th ed.) Citation

Keen, Martin L. The How and Why Wonder Book of Prehistoric Mammals. Wonder Books, 1962.

Warning: These citations may not always be 100% accurate.