%0 Journal Article
%A I. Yu. Popov
%T The Helmholtz resonator and the~theory of operator extensions in a~space with indefinite metric
%J Sbornik. Mathematics
%D 1993
%P 285-315
%V 75
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SM_1993_75_2_a0/
%G en
%F SM_1993_75_2_a0