Stebinger, Eugene. <br/><br/>
United States geological survey. Bulletin. Separata   

 - Washington-US :   Department of the interior,   1914. 
 - páginas 61-68 :   Ilustraciones blanco y negro 
 - Irregular 
 - (Oct. 1914) 
 - United States geological survey. Bulletin. Separata   .
 - Department of the interior. .