TY  - JOUR
AU  - M. Sh. Birman
AU  - A. Laptev
AU  - T. A. Suslina
TI  - The discrete spectrum of a~two-dimensional second-order periodic elliptic operator perturbed by a~decreasing potential.~I. A~semi-infinite gap
JO  - Algebra i analiz
PY  - 2000
SP  - 36
EP  - 78
VL  - 12
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/AA_2000_12_4_a2/
LA  - ru
ID  - AA_2000_12_4_a2
ER  -