Author
Geological Survey (U.S.)
2
Cravotta, Charles A., III
1
Dugas, Diana L.
1
Fishel, David K.,
1
Geological Survey (U.S.),
1
Pennsylvania. Bureau of Mining and Reclamation
1
Pennsylvania. Bureau of State Parks
1
Pennsylvania. Bureau of Topographic and Geologic Survey
1
Saad, David A.
1
Wood, Charles R.
1