APA
Pius XII, . (1939). Summi pontificatus. Encyclical letter of Pope Pius XII on the function of the state in the modern world : (official Vatican text). Derby: Apostolate of the Press.
Chicago
Pius XII, . 1939. Summi pontificatus. Encyclical letter of Pope Pius XII on the function of the state in the modern world : (official Vatican text). Derby: Apostolate of the Press.
Harvard
Pius XII, . (1939). Summi pontificatus. Encyclical letter of Pope Pius XII on the function of the state in the modern world : (official Vatican text). Derby: Apostolate of the Press.
MLA
Pius XII, . Summi pontificatus. Encyclical letter of Pope Pius XII on the function of the state in the modern world : (official Vatican text). Derby: Apostolate of the Press. 1939.
