by Samuel W. Berkheiser
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Directory of the nonfuel-mineral produce...
Fetid barite occurrences, western Berks ...
High-purity silica occurrences in Pennsy...
Reconnaissance survey of potential carbo...
The Chalk Man
Wild flowers of chalk & limestone
A Catalogue of the Organic Remains of th...
Conservation of Clay and Chalk Buildings
Sidewalk Rescue
Current oil and gas production from Nort...