APA (7e ed.) Bronvermelding

Não informado. (1999). United States Geological Survey annual report. U.S. Geological Survey.

Chicago (17e ed.) Bronvermelding

Não informado. United States Geological Survey Annual Report. Washington: U.S. Geological Survey, 1999.

MLA (8e ed.) Bronvermelding

Não informado. United States Geological Survey Annual Report. U.S. Geological Survey, 1999.

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