APA (7th ed.) Citation

Kagan, D. (2004). The Peloponnesian War. Penguin Books.

Chicago Style (17th ed.) Citation

Kagan, Donald. The Peloponnesian War. New York: Penguin Books, 2004.

MLA (9th ed.) Citation

Kagan, Donald. The Peloponnesian War. Penguin Books, 2004.