TY  - RPRT
TI  - A simplified economic filter for underground mining of massive sulfide deposits
AU  - D.A. Singer
AU  - W. D. Menzie
AU  - Keith R. Long
PY  - 2000
DO  - 10.3133/ofr00349
UR  - https://pubs.usgs.gov/publication/ofr00349
ID  - ofr00349
ER  -