%0 Journal Article
%A V. Yu. Popov
%T Direct and inverse inequalities for $\varphi$-Fej\'er mean-square approximations
%J Matematičeskie zametki
%D 1976
%P 353-364
%V 19
%N 3
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MZM_1976_19_3_a4/
%G ru
%F MZM_1976_19_3_a4