by Joseph J. Mathews. Issued also as thesis (Ph. D.) University of Pennsylvania. Main Heritage Shelves General DT107.6 .M3 1939 Book Item-ID: i10085038 B... Show moreby Joseph J. Mathews. Issued also as thesis (Ph. D.) University of Pennsylvania. Main Heritage Shelves General DT107.6 .M3 1939 Book Item-ID: i10085038 BIB-ID: 1010139 Bibliography: p. 129-134. Show less