APA (7th ed.) Citation

Pius XI, P. (1922). Apostolic Letter of Pope Pius XI, April 25, 1922. Washington, D.C..

Chicago Style (17th ed.) Citation

Pius XI, Pope. Apostolic Letter of Pope Pius XI, April 25, 1922. Washington, D.C., 1922.

MLA (8th ed.) Citation

Pius XI, Pope. Apostolic Letter of Pope Pius XI, April 25, 1922. Washington, D.C., 1922.

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