Zieselman, Ellen. <br/><br/>
UG: boys genius of the stone age and his search for soft trousers :   By Raymond Briggs, New York: Alfred A Knopf, 2001, 28 pages;  

 - Santa Fe-US :   Museum.  2003 
 - p. 26 :   il. 
 - Irregular 
 - Vol. 108, no. 4 (2003) 
 - El Palacio ;   vol.108(1) .
<br/><br/> En: For young readers.