Harvey Emmons, William.
The Enrichment of ore Deposits. - Washington-US : United States Geological Survey Bulletin, 1917. - páginas 3-530 : IIustraciones blanco y negro - No. 625 (1917) - United States Geological Survey Bulletin ; no.625 . - United States Geological Survey. .
The Enrichment of ore Deposits. - Washington-US : United States Geological Survey Bulletin, 1917. - páginas 3-530 : IIustraciones blanco y negro - No. 625 (1917) - United States Geological Survey Bulletin ; no.625 . - United States Geological Survey. .