%0 Journal Article
%A N. V. Assonova
%A V. D. Budaev
%T The Hilbert and Bessel properties of systems of eigenfunctions of second-order operators
%J Differencialʹnye uravneniâ
%D 2000
%P 147-151
%V 36
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_2000_36_2_a0/
%G ru
%F DE_2000_36_2_a0