International yearbook of education, Vol. XXI, 1959. 

 - Geneva :  Paris :  IBE;  UNESCO,,  1959. 
 - 550 p. 
 - IBE publication ;  212. .
<br/><br/><label>No. de Clasificación Universal Decimal: </label>OC 37 (100) =20 "1959" INN Vol. 21