Sagan, Hans. , <br/><br/>
Boundary and eigenvalue problems in mathematical physics 

 - New York:  Dover Publication,  1989. 
 - xviii, 381 p.:   ill.;  22 cm. 
<br/><br/> Reprint. Originally published: New York : Wiley, 1961.  
<br/><br/><label>ISBN: </label>9780486661322 
<br/><br/><label>Dewey Class. No.: </label>530.15535 SAG