Não informado. (1999). United States Geological Survey annual report. U.S. Geological Survey.
Style de citation Chicago (17e éd.)Não informado. United States Geological Survey Annual Report. Washington: U.S. Geological Survey, 1999.
Style de citation MLA (8e éd.)Não informado. United States Geological Survey Annual Report. U.S. Geological Survey, 1999.
Attention : ces citations peuvent ne pas être correctes à 100%.