%0 Journal Article
%A M. D. Kovalenko
%T Biorthogonal expansions in eigenfunctions. I
%J Differencialʹnye uravneniâ
%D 1987
%P 1764-1772
%V 23
%N 10
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1987_23_10_a12/
%G ru
%F DE_1987_23_10_a12