TY  - JOUR
AU  - M. Sh. Birman
TI  - Perturbation of the spectrum of a singular elliptic operator under variation of the boundary and boundary conditions
JO  - Doklady Akademii Nauk
PY  - 1961
SP  - 761
EP  - 763
VL  - 137
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1961_137_4_a0/
LA  - ru
ID  - DAN_1961_137_4_a0
ER  -