Modern languages atgeneral secondary schools; research in comparative educatio-. 

 - Paris : UNESCO; Geneva : IBE, 1964. 
 - xlvii, 189 p. 
 - UNESCO-IBE publications, 268 .
<br/><br/><label>No. de Clasificación Universal Decimal: </label>372.88 (100)=20 "1964" MOD No.268.