TY  - JOUR
AU  - O. L. Safronov
TI  - Emergence and disappearance of the discrete spectrum in a gap of a second-order periodic operator under decreasing perturbations with alternating signs
JO  - Algebra i analiz
PY  - 1997
SP  - 148
EP  - 166
VL  - 9
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/AA_1997_9_1_a5/
LA  - ru
ID  - AA_1997_9_1_a5
ER  -