APA (7th ed.) Zitazioa
Allen, W. L. National Geographic: Vol. 193, no. 2, February 1998. National Geographic Society.
Chicago Style (17th ed.) Zitazioa
Allen, William L. National Geographic: Vol. 193, No. 2, February 1998. Washington, EUA: National Geographic Society.
MLA (9th ed.) Zitazioa
Allen, William L. National Geographic: Vol. 193, No. 2, February 1998. National Geographic Society.
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