APA (7th ed.) Zitazioa
Gagern, F. E. (1969). Enzyklika Humanae vitae - was nun? Manz.
Chicago Style (17th ed.) Zitazioa
Gagern, Friedrich Ernst. Enzyklika Humanae Vitae - Was Nun? München: Manz, 1969.
MLA (9th ed.) Zitazioa
Gagern, Friedrich Ernst. Enzyklika Humanae Vitae - Was Nun? Manz, 1969.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.