Cita APA (7a ed.)

Paul VI, P. (1968). On the regulation of birth = Humanae vitae: Encyclical letter. Washington, D.C..

Cita Chicago Style (17a ed.)

Paul VI, Pope. On the Regulation of Birth = Humanae Vitae: Encyclical Letter. Washington, D.C., 1968.

Cita MLA (8a ed.)

Paul VI, Pope. On the Regulation of Birth = Humanae Vitae: Encyclical Letter. Washington, D.C., 1968.