Catholic Church. Pope (1922-1939 : Pius XI) & Pius XI, P. (1932). The light of truth: Concerning the celebration of the fifteenth centenary of the Oecumenical Council of Ephesus : encyclical letter (Lux veritatis) of His Holiness, Pope Pius XI : (Vatican Press translation) : issued December 25, 1931. National Catholic Welfare Conference.
Chicago Style (17th ed.) CitationCatholic Church. Pope (1922-1939 : Pius XI) and Pope Pius XI. The Light of Truth: Concerning the Celebration of the Fifteenth Centenary of the Oecumenical Council of Ephesus : Encyclical Letter (Lux Veritatis) of His Holiness, Pope Pius XI : (Vatican Press Translation) : Issued December 25, 1931. Washington, D.C.: National Catholic Welfare Conference, 1932.
MLA (8th ed.) CitationCatholic Church. Pope (1922-1939 : Pius XI) and Pope Pius XI. The Light of Truth: Concerning the Celebration of the Fifteenth Centenary of the Oecumenical Council of Ephesus : Encyclical Letter (Lux Veritatis) of His Holiness, Pope Pius XI : (Vatican Press Translation) : Issued December 25, 1931. National Catholic Welfare Conference, 1932.