Não informado. (2013). U.S. Geological Survey Circular. U.S. Geological Survey.
Chicago Style (17th ed.) CitationNão informado. U.S. Geological Survey Circular. Reston, Va: U.S. Geological Survey, 2013.
MLA (8th ed.) CitationNão informado. U.S. Geological Survey Circular. U.S. Geological Survey, 2013.
Warning: These citations may not always be 100% accurate.