Winkel, W.S. <br/><br/>
Psikologi pengajaran / 
W.S. Winkel. 
 - Jakarta :  Pt.Gramedia,  1987. 
 - 389 p. :  ill. ;  24 cm. 
<br/><br/>p. 387-388 
<br/><br/><label>ISBN: </label>X920047077 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Educational psychology.