Voskuil, Walter. <br/><br/>
The first century and a quarter of american coal industry. 

 - New York-US :   Geografical record,   1943. 
 - páginas 164-165 :   Ilustraciones blanco y negro 
 - Irregular 
 - Vol. XXXIII, no. 1(Jan. 1943) 
 - The Geographical Review ;   no. 1 .
 - The Geographical Review. .
<br/><br/> Artículo dentro de: Geographical reviews.