%0 Journal Article
%A S. I. Novikov
%T Widths of a class of periodic functions defined by a differential operator
%J Matematičeskie zametki
%D 1987
%P 194-206
%V 42
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MZM_1987_42_2_a3/
%G ru
%F MZM_1987_42_2_a3