TY  - BOOK
AU  - Emmons,William H.
TI  - The enrichment of ore deposits
T2  - U.s. geological survey. bulletin
AV  - TN263 E55
PY  - 1917///
CY  - Washington
PB  - Goverment printing office
KW  - Yacimientos minerales
N1  - A la cabeza de la portada: department of the interior
ER  -