Elsgolc L.E <br/><br/>
Calcalus of variations 

 - London  Pergamon Press           1961 
 - 178p  cm. 
 - Adiwes International Series in Mathematics .
<br/><br/><label>Source: </label> General Book 
<br/><br/><label>Dewey Class. No.: </label>B42, K1/SC