Trythall, Marisa Patrulli (2010). "Pius XI and American Pragmatism". In Gallagher, Charles R.; Kertzer, David I.; Melloni, Alberto (eds.). Pius XI and America: Proceedings of the Brown University Conference. Lit Verlag. p. 28. ISBN978-3-643-90146-0. Archived from the original on 9 February 2018.
Peter C. Kent, "A Tale of Two Popes: Pius XI, Pius XII and the Rome-Berlin Axis", Journal of Contemporary History (1988) 23#4 pp 589–608 in JSTORArchived 7 January 2017 at the Wayback Machine
Pope Pius XI (1 March 1922). "Cum proxime" (in Italian). Libreria Editrice Vaticana. Archived from the original on 28 December 2017. Retrieved 1 November 2017. {{cite journal}}: Cite journal requires |journal= (help)
Pope Pius XI (18 November 1926). "Iniquis afflictisque". Archived from the original on 8 November 2009. Retrieved 21 October 2009.
w2.vatican.va
Pope Pius XI (30 September 1928). "Motu Proprio Quod Maxime". w2.vatican.va. Archived from the original on 9 February 2018. Retrieved 20 December 2017.
Trythall, Marisa Patrulli (2010). "Pius XI and American Pragmatism". In Gallagher, Charles R.; Kertzer, David I.; Melloni, Alberto (eds.). Pius XI and America: Proceedings of the Brown University Conference. Lit Verlag. p. 28. ISBN978-3-643-90146-0. Archived from the original on 9 February 2018.
Pope Pius XI (1 March 1922). "Cum proxime" (in Italian). Libreria Editrice Vaticana. Archived from the original on 28 December 2017. Retrieved 1 November 2017. {{cite journal}}: Cite journal requires |journal= (help)
"Storia del P.I.O."Orientale (in Italian). Archived from the original on 22 December 2017. Retrieved 20 December 2017.
Pope Pius XI (30 September 1928). "Motu Proprio Quod Maxime". w2.vatican.va. Archived from the original on 9 February 2018. Retrieved 20 December 2017.
Peter C. Kent, "A Tale of Two Popes: Pius XI, Pius XII and the Rome-Berlin Axis", Journal of Contemporary History (1988) 23#4 pp 589–608 in JSTORArchived 7 January 2017 at the Wayback Machine