Learning: the treasure within :  Report to UNESCO of the International Commission on Education for the Twenty-first Century / 
by Jacques Delors...(et al.). 
 - Paris :  UNESCO,  1996. 
 - 266 p. 
<br/><br/><label>ISBN: </label>0119843870 (HMSO) 9231032747 
<br/><br/><label>No. de Clasificación Universal Decimal: </label>37 "313" (100) =20 EDU