The Devonian of Pennsylvania :  Middle and upper Devonian / 
by Bradford Willard; Keyser limestone and Helderberg group, by Frank M. Swartz; Oriskany group, by Arthur B. Cleaves. 
 - Harrisburg, Pa. :  Dept. of internatl affairs, Topographic and geologic survey,  1939. 
 - xii, 481 p. :  ill. ;  24 cm. 
 - Bulletin G ;  19 .
<br/><br/> At head of title: Pennsylvania Geological Survey, Fourth series. 
<br/><br/>Bibliography: p. 434-445. 
<br/><br/><label>LCCN: </label>gs 39000291  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Geology, Stratigraphic--Devonian.<br/>Geology--Pennsylvania.<br/>Paleontology--Devonian.
<br/><br/><label>LC Class. No.: </label>QE665  / .P42 1939