Helmberg, Gilbert <br/><br/>
Introduction to spectral theory in hilbert space 

 - Oxford  North-Holland  1975 
 - xiii,346p, 22cm 
 - North-Holland series in applied mathematics and mechanics .
<br/><br/><label>ISBN: </label>0720423503 
<br/><br/><label>Dewey Class. No.: </label>515.733,  / D, hel