Dyfyniad APA

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

Dyfyniad Arddull Chicago

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

Dyfyniad MLA

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

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