Harvey Emmons, William. <br/><br/>
United States Geological Survey Bulletin ;   no.625 

 - Washington-US :   United States Geological Survey Bulletin,   1917. 
 - páginas 3-530 :   IIustraciones blanco y negro 
 - No. 625 (1917) 
 - United States Geological Survey Bulletin ;   no.625 .
 - United States Geological Survey. .