Campbell, Marius H. - Bownocker, J. A. <br/><br/>
The coal fields of the united states :   General Introduction. Ohio. 

 - Washington  Government Printing Office  1929 
 - 101 p. 
<br/><br/> Impreso 
<br/><br/><br/>Ingles 
<br/><br/><label>Subjects--Topical Terms: </label><br/>MINERIA