Cita APA (7a ed.)
Graves, W. National Geographic: Vol. 179, no. 1, January 1991. National Geographic Society.
Cita estilo Chicago (17a ed.)
Graves, William. National Geographic: Vol. 179, No. 1, January 1991. Washington, EUA: National Geographic Society.
Cita MLA (9a ed.)
Graves, William. National Geographic: Vol. 179, No. 1, January 1991. National Geographic Society.
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