Author
Darlington, William, 1782-1863
2
Chester County Cabinet of Natural Science (West Chester, Pa.)
1
Delaware Geological Survey
1
Delaware. Department of Natural Resources and Environmental Control
1
Delaware. Division of Parks and Recreation
1
Discover Brandywine Valley Public Relations Association
1
Faill, Rodger T.
1
Overdevest, Gaye
1
Parish, Charles W.
1
Penn Bureau of State Parks
1
Penn Bureau of Topographic and Geologic Survey.Pennsylvania Bureau of State Parks
1
Penn Dept. of Environmental Resources
1
Pennsylvania Bureau of State Parks White Clay Creek Preserve
1
Pennsylvania Dept. of Conservation and Natural Resources Bureau of State Parks
1