APA (7th ed.) Citation

Nichols, J. P. (1943). Twentieth century United States: A history. D. Appleton-Century.

Chicago Style (17th ed.) Citation

Nichols, Jeanette Paddok. Twentieth Century United States: A History. New York: D. Appleton-Century, 1943.

MLA (9th ed.) Citation

Nichols, Jeanette Paddok. Twentieth Century United States: A History. D. Appleton-Century, 1943.