Não informado. (2011). U.S. Geological Survey Bulletin. U.S. Department of the Interior, Geological Survey.
Chicago-Zitierstil (17. Ausg.)Não informado. U.S. Geological Survey Bulletin. Washington: U.S. Department of the Interior, Geological Survey, 2011.
MLA-Zitierstil (8. Ausg.)Não informado. U.S. Geological Survey Bulletin. U.S. Department of the Interior, Geological Survey, 2011.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.