Friedrichs K.O. <br/><br/>
Spectral Theory of Operators in Hilbert Space. 
Friedrichs K.O. 
 - New York-Heidelberg-Berlin  Springer-Verlag  1980 
 - 244 p. 
<br/><br/> Applied Mathematical Sciences, Vol. 9 
<br/><br/><label>Dewey Class. No.: </label>517.984