APA (7th ed.) Citation

Catholic Church. Pope (1939-1958 : Pius XII) & Pius XII, P. (1940). Encyclical letter to the American hierarchy. Paulist Press.

Chicago Style (17th ed.) Citation

Catholic Church. Pope (1939-1958 : Pius XII) and Pope Pius XII. Encyclical Letter to the American Hierarchy. [New York: Paulist Press, 1940.

MLA (8th ed.) Citation

Catholic Church. Pope (1939-1958 : Pius XII) and Pope Pius XII. Encyclical Letter to the American Hierarchy. Paulist Press, 1940.

Warning: These citations may not always be 100% accurate.