TY  - BOOK
AU  - Filippov V M
AU  - Schulenberger J R
TI  - Variational principles for non-potential operators
U1  - 510TM 
PY  - 1989///
CY  - Providence
PB  - AMS
KW  - Mathematics
KW  - Operator theory
N1  - Tr from Russian
ER  -