The Unity of Human Society, Encyclical of Pope Pius XII (Summi Pontificatus), Arranged for Study Clubs with Questions and References; The America Press, New York, 1939/1108, PGEN 132/5870. General Collection, GEN. University of Notre Dame Archives. https://archivesspace.library.nd.edu/repositories/2/archival_objects/1097537 Accessed November 24, 2024.