Cita APA (7a ed.)

Pius X, P. (1904). The XIII Centenary of St. Gregory, Encyclical Letter of Pius X. New York.

Cita Chicago Style (17a ed.)

Pius X, Pope. The XIII Centenary of St. Gregory, Encyclical Letter of Pius X. New York, 1904.

Cita MLA (8a ed.)

Pius X, Pope. The XIII Centenary of St. Gregory, Encyclical Letter of Pius X. New York, 1904.