Cita APA (7a ed.)

Pius X, P. (1910). The Mortu proprio of Pope Pius X: Dated June 29, 1910 [i.e. Sept. 1, 1910]. [Open Court?].

Cita Chicago Style (17a ed.)

Pius X, Pope. The Mortu Proprio of Pope Pius X: Dated June 29, 1910 [i.e. Sept. 1, 1910]. [Chicago?]: [Open Court?], 1910.

Cita MLA (8a ed.)

Pius X, Pope. The Mortu Proprio of Pope Pius X: Dated June 29, 1910 [i.e. Sept. 1, 1910]. [Open Court?], 1910.