Ubi arcano. [Encycliek 23 dec. 1922].

MLA

Pius. Ubi Arcano. [encycliek 23 Dec. 1922]. Fribourg: St-Paul, 1958.

APA

Pius, P. (1958). Ubi arcano. [Encycliek 23 dec. 1922]. Fribourg: St-Paul.

Chicago

Pius Ubi Arcano. [encycliek 23 Dec. 1922]. Fribourg: St-Paul, 1958.