Notes comments & letter to the editor or some frequently occuing error in the economic literator concering problems of maximum & minium 

 - s.l  s.n.           
<br/><br/><label>Source: </label> General Book 
<br/><br/><label>Dewey Class. No.: </label>X:(b).72.N75, L5.134-39,142-45, 147-48