Matthews, JR. Kenneth D. <br/><br/>
Saffrom and swan's grease. 

 - Pennsilvania-US :   Univesity of Pennsylvania,   1963.. 
 - páginas11-17 :   ilustraciones blanco y negro 
 - Trimenstral 
 - Vol.5 no 4 (1963)  
 - Expedition. the bulletin of the university museum of the university of pennsilvania ;   no. 4 .
 - University of Pennsylvania. .