Author
Geological Survey of Pennsylvania
3
Lyman, Benjamin Smith, 1835-1920
3
Pennsylvania. Department of Conservation and Natural Resources
3
Dodge, Clifford H.
2
Genth, F. A. 1820-1893
2
Lesley, J. P. 1819-1903
2
Foster, William S.
1
Foster, Wm. B.
1
Lehigh Coal and Navigation Co
1
Lesquereux, Leo, 1806-1889
1
Pennsylvania State Geologist (1836-1841)
1
Rogers, Henry D. 1808-1866
1
Rogers, Henry Darwin, 1808-1866
1
Rogers, William Barton, 1804-1882
1
Rothwell, Richard Pennefather, 1836-1901
1
Shaulis, James R.
1