Lavrent'ev,M.A. <br/><br/>
Variational methods for boundary value problems for systems of elliptic equation / 
Lavrent'ev,M.A. 
 - New York:  Dover publications,  1989. 
 - 153p;26cm 
<br/><br/>Includes bibliographical references. 
<br/><br/><label>ISBN: </label>0486661709 
<br/><br/><label>Dewey Class. No.: </label>515.35 LAV