APA (7th ed.) Zitazioa
Harnack, A. (1957). What is Christianity? Peter Smith Publishers.
Chicago Style (17th ed.) Zitazioa
Harnack, Adolf. What Is Christianity? U.S.A: Peter Smith Publishers, 1957.
MLA (9th ed.) Zitazioa
Harnack, Adolf. What Is Christianity? Peter Smith Publishers, 1957.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.