Não informado. (1985). National Geographic Research. National Geographic Society.
Chicago (17e ed.) BronvermeldingNão informado. National Geographic Research. Gaithersburg, Md: National Geographic Society, 1985.
MLA (8e ed.) BronvermeldingNão informado. National Geographic Research. National Geographic Society, 1985.
Let op: Deze citaties zijn niet altijd 100% accuraat.