International yearbook of education, Vol. XX, 1958. 

 - Geneva :  Paris :  IBE,  UNESCO,  1958. 
 - 432 p. 
 - IBE publication ;  202. .
<br/><br/><label>No. de Clasificación Universal Decimal: </label>OC 37 (100) =20 "1958" INN Vol. 20