APA (7th ed.) Citation

Pius XI, p. Ex motu propio de Pontificia Academia scientiarum.

Chicago Style (17th ed.) Citation

Pius XI, papa. Ex Motu Propio De Pontificia Academia Scientiarum. [s.n.t.].

MLA (9th ed.) Citation

Pius XI, papa. Ex Motu Propio De Pontificia Academia Scientiarum.

Warning: These citations may not always be 100% accurate.