Catholic Church. Pope (1922-1939 : Pius XI), Pius, X., & Treacy, G. C. (1930). Christian education of youth: Encyclical letter. Paulist Press.
Chicago-viite (17. p.)Catholic Church. Pope (1922-1939 : Pius XI), XI Pius, ja Gerald C. Treacy. Christian Education of Youth: Encyclical Letter. New York, N.Y.: Paulist Press, 1930.
MLA-viite (8. p.)Catholic Church. Pope (1922-1939 : Pius XI), et al. Christian Education of Youth: Encyclical Letter. Paulist Press, 1930.
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