Columbia encyclopedia 

 - 2nd 
 -  1950 
<br/><br/><label>Standard No.: </label>31274 
<br/><br/><label>Source: </label> Textual 
<br/><br/><label>Subjects--Topical Terms: </label><br/>SECONDARY EDUCATION
<br/><br/><label>Dewey Class. No.: </label>373:N35, J0   RR