Ashley, Geo. H.  1866- <br/><br/>
The undeveloped mineral resources of Pennsylvania / 
introduction by George H. Ashley. 
 - Harrisburg, Pa. :  Department of internal affairs, Topographic and geologic survey,  1933. 
 - 16 p. :  incl. tables ;  23 cm. 
 - Pennsylvania. Geological survey, 4th (1919-  ) Bulletin M18-A .
 - Bulletin M ;  18-A. .
<br/><br/> At head of title: Pennysylvania Geological survey, Fourth series. 
<br/><br/><label>LCCN: </label>gs 38000043  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Mines and mineral resources--Pennsylvania.
<br/><br/><label>LC Class. No.: </label>TN24.P4  / A7