APA (7th ed.) Citation
Graves, W. National Geographic: Vol. 179, no. 4, April 1991. National Geographic Society.
Chicago Style (17th ed.) Citation
Graves, William. National Geographic: Vol. 179, No. 4, April 1991. Washington, EUA: National Geographic Society.
MLA (9th ed.) Citation
Graves, William. National Geographic: Vol. 179, No. 4, April 1991. National Geographic Society.
Warning: These citations may not always be 100% accurate.