TY  - RPRT
TI  - Photographs of historical mining operations in Colorado and Utah from the U.S. Geological Survey Library
AU  - Joseph K. McGregor
AU  - C. C. Abston
PY  - 1994
DO  - 10.3133/ds12
UR  - https://pubs.usgs.gov/publication/ds12
ID  - ds12
ER  -