Existence theorems in partial differential equations 
Bernstein, Dorothy Lewis, 
 - Princeton,  Princeton University Press, 
 - vii, 228 p.  26 cm. 
 - under contract N6onr-240."  no. 23 .
<br/><br/> Prepared for the Office of Naval Research by Engineering Research Associates 
<br/><br/><label>ISBN: </label>691095809