Citazione Stile APA (7a Edizione)

Ridge, M., & Billington, R. A. (1969). America's frontier story: A documentary history of westward expansion. Holt, Rinehart and Winston.

Citazione stile Chigago Style (17a edizione)

Ridge, Martin, e Ray Allen Billington. America's Frontier Story: A Documentary History of Westward Expansion. New York: Holt, Rinehart and Winston, 1969.

Citatione MLA (9a ed.)

Ridge, Martin, e Ray Allen Billington. America's Frontier Story: A Documentary History of Westward Expansion. Holt, Rinehart and Winston, 1969.