Wigglesworth Clarke, Frank. <br/><br/>
United States Geological Survey Bulletin ;   no.588 

 - Washington-US :   United States Geological Survey Bulletin,   1914. 
 - páginas 3-128 :   IIustraciones blanco y negro 
 - No. 588 (1914) 
 - United States Geological Survey Bulletin ;   no.588 .
 - United States Geological Survey. .