TY  - RPRT
TI  - A digital resource model of the Upper Pennsylvanian Pittsburgh coal bed, Monongahela Group, northern Appalachian basin coal region, USA
AU  - L.F. Ruppert
AU  - S.J. Tewalt
AU  - L. J. Bragg
AU  - R.N. Wallack
PY  - 1999
DO  - 10.1016/s0166-5162(99)00009-9
UR  - https://pubs.usgs.gov/publication/70021874
ID  - 70021874
ER  -