Emmons, William Harvey <br/><br/>
The principles of economic geology 

 - New York  McGraw-hill Book Company  1918 
 - 606 p.  ilus. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>GEOLOGIA ECONOMICA<br/>YACIMIENTOS MINERALES
<br/><br/><label>Universal Decimal Class. No.: </label>553/E52