TY  - RPRT
TI  - Copper-Zinc deposits of the Penn Mine Calaveras County, California
AU  - George Richard Heyl
AU  - M.W. Cox
AU  - J. H. Eric
PY  - 1945
DO  - 10.3133/ofr4551
UR  - https://pubs.usgs.gov/publication/ofr4551
ID  - ofr4551
ER  -