Advances in motivation and achievement :  a research annual / 
ed. Martin L. Maehr. 
 - Greenwich, E.U.A. :  JAI,  1991. 
 - 417 p. 
 - Advances in motivation and achievement ;  7 .
<br/><br/><label>ISBN: </label>1559381221 
<br/><br/><label>Encabezamiento--Tema: </label><br/>Motivación (Psicología)