Pius X, P. (1904). The XIII Centenary of St. Gregory, Encyclical Letter of Pius X. New York.
Chicago (17e ed.) BronvermeldingPius X, Pope. The XIII Centenary of St. Gregory, Encyclical Letter of Pius X. New York, 1904.
MLA (8e ed.) BronvermeldingPius X, Pope. The XIII Centenary of St. Gregory, Encyclical Letter of Pius X. New York, 1904.
Let op: Deze citaties zijn niet altijd 100% accuraat.