APA (7e ed.) Bronvermelding
Graves, W. National Geographic: Vol. 179, no. 6, June 1991. National Geographic Society.
Chicago (17e ed.) Bronvermelding
Graves, William. National Geographic: Vol. 179, No. 6, June 1991. Washington, EUA: National Geographic Society.
MLA (9e ed.) Bronvermelding
Graves, William. National Geographic: Vol. 179, No. 6, June 1991. National Geographic Society.
Let op: Deze citaties zijn niet altijd 100% accuraat.