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USA | |
| Butler, Bert Sylvenus (1941) Ore deposits in the vicinity of the London fault of Colorado. USGS Bulletin: 911 Singewald, Quentin Dreyer |
| Butler, Bert Sylvenus (1941) Ore deposits in the vicinity of the London fault of Colorado. USGS Bulletin: 911 Singewald, Quentin Dreyer |
| Eckel, Edwin Butt , Cobban, Robert R., Mosburg, Shirley K., Foord, Eugene E. (1997) Minerals of Colorado. Fulcrum Publishing. |
- Horseshoe Basin Mining District
| Erich Laskowski Collection |
| Eckel, Edwin Butt , Cobban, Robert R., Mosburg, Shirley K., Foord, Eugene E. (1997) Minerals of Colorado. Fulcrum Publishing. |
| Butler, Bert Sylvenus (1941) Ore deposits in the vicinity of the London fault of Colorado. USGS Bulletin: 911 Singewald, Quentin Dreyer |
| Eckel, Edwin Butt , Cobban, Robert R., Mosburg, Shirley K., Foord, Eugene E. (1997) Minerals of Colorado. Fulcrum Publishing. |
| Eckel, Edwin Butt , Cobban, Robert R., Mosburg, Shirley K., Foord, Eugene E. (1997) Minerals of Colorado. Fulcrum Publishing. |