TY  - RPRT
TI  - The Upper Pennsylvanian Pittsburgh coal bed: Resources and mine models
AU  - W.D. Watson
AU  - L.F. Ruppert
AU  - S.J. Tewalt
AU  - L. J. Bragg
PY  - 2001
DO  - 10.1023/a:1011529430807
UR  - https://pubs.usgs.gov/publication/70022814
ID  - 70022814
ER  -