TY  - JOUR
AU  - V. A. Il'in
TI  - Conditions for the convergence of spectral decompositions that correspond to selfadjoint extensions of elliptic operators. IV.~Theorems of negative type for an arbitrary extension of a general second order selfadjoint elliptic operator
JO  - Differencialʹnye uravneniâ
PY  - 1973
SP  - 49
EP  - 73
VL  - 9
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1973_9_1_a6/
LA  - ru
ID  - DE_1973_9_1_a6
ER  -