... Final Report Ordered by Legislature, 1891. A Summary Description of the Geology of Pennsylvania, in Three Volumes, With a New Geological Map of the State, a Map and List of Bituminous Mines ..

... Final Report Ordered by Legislature, 1891. A Summary Description of the Geology of Pennsylvania, in Three Volumes, With a New Geological Map of the State, a Map and List of Bituminous Mines ..