Structure-contour maps of the plateau region of north-central and western Pennsylvania.

by Fettke, Charles R. (Charles Reinhard), 1888-1959
[Harrisburg, Pa.] : Dept. of Internal Affairs, Topographic and Geologic Survey, 1954

Subsurface projection of Cambro-Ordovician sediments in the Pennsylvania-New York region.

by Swartz, Frank M. (Frank McKim), 1899-1982
Harrisburg : Commonwealth of Pennsylvania, Dept. of Internal Affairs, Topographic and Geologic Survey, 1950