TY  - JOUR
AU  - I. Yu. Popov
TI  - The Helmholtz resonator and the theory of operator extensions in a space with indefinite metric
JO  - Sbornik. Mathematics
PY  - 1993
SP  - 285
EP  - 315
VL  - 75
IS  - 2
UR  - http://geodesic.mathdoc.fr/item/SM_1993_75_2_a0/
LA  - en
ID  - SM_1993_75_2_a0
ER  -