APA (7th ed.) Zitazioa
Grosvenor, G. M. National geographic: December 1978. National Geographic Society.
Chicago Style (17th ed.) Zitazioa
Grosvenor, Gilbert M. National Geographic: December 1978. Washington, EUA: National Geographic Society.
MLA (9th ed.) Zitazioa
Grosvenor, Gilbert M. National Geographic: December 1978. National Geographic Society.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.