TY  - RPRT
TI  - Map showing generalized thickness contours of the Pittsburgh coal bed in Pennsylvania, Ohio, West Virginia, and Maryland
AU  - S. J. Tewalt
AU  - L.F. Ruppert
AU  - L. J. Bragg
AU  - Richard Carlton
AU  - David Brezinski
AU  - R.N. Wallack
PY  - 1997
DO  - 10.3133/ofr97748
UR  - https://pubs.usgs.gov/publication/ofr97748
ID  - ofr97748
ER  -