Citazione Stile APA (7a Edizione)

Billington, R. A. (1960). Westward expansion: A history of the American frontier (2nd ed.). Macmillan.

Citazione stile Chigago Style (17a edizione)

Billington, Ray Allen. Westward Expansion: A History of the American Frontier. 2nd ed. New York: Macmillan, 1960.

Citatione MLA (9a ed.)

Billington, Ray Allen. Westward Expansion: A History of the American Frontier. 2nd ed. Macmillan, 1960.