Youngdahl, David M., Lauber, Yvone & Furukawa, Mel  1967. <br/><br/>
Position and motion:  A science unit for the upper elementary /  
by David, M. Youngdahl; Yvonne Lauber and Mel furukawa 
 - California:   University of Carifornia Berkeley,  1967. 
 - 60 pages:  illustrations;  28 cm.