APA (7th ed.) Citation

(1957). The unhappy hippopotamus. Vanguard Press.

Chicago Style (17th ed.) Citation

The Unhappy Hippopotamus. New York: Vanguard Press, 1957.

MLA (9th ed.) Citation

The Unhappy Hippopotamus. Vanguard Press, 1957.

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