APA (7th ed.) Citation

Diffie, B. W., & Diffie, J. W. (1931). Puerto Rico: A broken pledge. The Vanguard Press.

Chicago Style (17th ed.) Citation

Diffie, Bailey W., and Justine Whitfield Diffie. Puerto Rico: A Broken Pledge. New York: The Vanguard Press, 1931.

MLA (9th ed.) Citation

Diffie, Bailey W., and Justine Whitfield Diffie. Puerto Rico: A Broken Pledge. The Vanguard Press, 1931.