APA (7th ed.) Citation

Humphrey, E. F. (1931). An economic history of the United States. The Century Co..

Chicago Style (17th ed.) Citation

Humphrey, Edward Frank. An Economic History of the United States. New York: The Century Co., 1931.

MLA (9th ed.) Citation

Humphrey, Edward Frank. An Economic History of the United States. The Century Co., 1931.