Sparkes, W.E. <br/><br/>
Lessons o shading / 
W.E. Sparkes 
 - New York :  Dover Publications, Inc.  2007. 
<br/><br/><label>ISBN: </label>978-0-486-45451-1 
<br/><br/><label>Dewey Class. No.: </label>CIR  741.2 Sp261 2007