TY  - JOUR
AU  - V. I. Filippenko
TI  - Some criteria for discreteness of the negative part of the spectrum of a linear differential operator
JO  - Differencialʹnye uravneniâ
PY  - 1985
SP  - 728
EP  - 731
VL  - 21
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1985_21_4_a23/
LA  - ru
ID  - DE_1985_21_4_a23
ER  -