U.S. Geological Survey. Mineral industry surveys , copper in april 2006.
Cita Chicago Style (17a ed.)U.S. Geological Survey. Mineral Industry Surveys , Copper in April 2006.
Cita MLA (9a ed.)U.S. Geological Survey. Mineral Industry Surveys , Copper in April 2006.
Precaución: Estas citas no son 100% exactas.