Kato, Tosio. <br/><br/>
Perturbation theory for linear operations   
by Tosio Kato 
 - 2nd 
 - Berlin  Springer Verlag  1976 
 - xvii, 619p. 
 - Grundlehren der mathematischen Wissenschaften  Band 132 .
<br/><br/><label>ISBN: </label>3540075585 
<br/><br/><label>Dewey Class. No.: </label>515.72  / N761