%0 Journal Article
%A V. A. Il'in
%T Properties of spectra of nonnegative self-adjoint extensions of elliptic operators and exact conditions for the convergence and Riesz summability of Fourier series of various classes of functions
%J Matematičeskie zametki
%D 1970
%P 515-523
%V 7
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MZM_1970_7_4_a16/
%G ru
%F MZM_1970_7_4_a16