Salvatore, Dominick. <br/><br/>
Theory and Problems of Microeconomic Theory /  

 - S.I. Ed. /  
 - Singapore :   McGraw-Hill Book Company. 
 - p.326 :  
<br/><br/><label>ISBN: </label>0-07-099070-0 
<br/><br/><label>Dewey Class. No.: </label>X:76  / M3;4