Diffie, B. W., & Diffie, J. (1931). Porto Rico: A broken pledge. The Vanguard Press.
Chicago Style (17th ed.) CitationDiffie, Bailey Wallys, and Justine Diffie. Porto Rico: A Broken Pledge. New York: The Vanguard Press, 1931.
MLA (9th ed.) CitationDiffie, Bailey Wallys, and Justine Diffie. Porto Rico: A Broken Pledge. The Vanguard Press, 1931.
Warning: These citations may not always be 100% accurate.