%0 Journal Article
%A V. A. Il'in
%T 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
%J Differencialʹnye uravneniâ
%D 1973
%P 49-73
%V 9
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1973_9_1_a6/
%G ru
%F DE_1973_9_1_a6