Friedrichs, K.D. <br/><br/>
Spectral theory of operators in Hilbert space 
by K.D. Friedrichs 
 - New York  Springer-Verlag  1973 
 - viii,244p.;  26cm.- 
 - Applied mathematical sciences; no.9 .
<br/><br/><label>Dewey Class. No.: </label>515.73  / FRI