Symposium on Middle and Upper Devonian stratigraphy of Pennsylvania and adjacent states. /

Harrisburg : [Available from the Bureau of Publications, Dept. of Property and Supplies], 1963

Stratigraphy of the Cambrian to Middle Ordovician rocks of central and western Pennsylvania /

by Wagner, Walter Richard, 1928-1974
Harrisburg : [Dept. of Internal Affairs, Bureau of Topographic and Geologic Survey], 1966