Cita APA (7th ed.)
Garret, W. E. National Geographic: Vol. 177, no. 1, January 1990. National Geographic Society.
Cita Chicago (17th ed.)
Garret, Wilbur E. National Geographic: Vol. 177, No. 1, January 1990. Washington, EUA: National Geographic Society.
Cita MLA (9th ed.)
Garret, Wilbur E. National Geographic: Vol. 177, No. 1, January 1990. National Geographic Society.
Atenció: Aquestes cites poden no estar 100% correctes.