Cita APA (7th ed.)

Whitney, D. C., & Whitney, R. V. (1990). The American presidents (7th ed.). Prentice Hall Press.

Cita Chicago (17th ed.)

Whitney, David C., i Robin Vaughn Whitney. The American Presidents. 7th ed. New York: Prentice Hall Press, 1990.

Cita MLA (9th ed.)

Whitney, David C., i Robin Vaughn Whitney. The American Presidents. 7th ed. Prentice Hall Press, 1990.