TY  - BOOK
AU  - Helmberg Gilbert
TI  - Introduction to spectral theory in hilbert space
T2  - North-Holland series in applied Mathematics and Mechanics; 6
U1  - B313N, L5    TTB 
PY  - 1975///
CY  - Amsterdam
PB  - North-Holland       
KW  - Hilbert space
ER  -