APA (7e ed.) Bronvermelding

Não informado. (1985). National Geographic Research. National Geographic Society.

Chicago (17e ed.) Bronvermelding

Não informado. National Geographic Research. Gaithersburg, Md: National Geographic Society, 1985.

MLA (8e ed.) Bronvermelding

Não informado. National Geographic Research. National Geographic Society, 1985.

Let op: Deze citaties zijn niet altijd 100% accuraat.