%0 Journal Article
%A S. Ya. Havinson
%T A~Chebyshev theorem for the approximation of a~function of two variables by sums of the type $\varphi(x)+\psi(y)$
%J Izvestiya. Mathematics 
%D 1969
%P 617-632
%V 3
%N 3
%I mathdoc
%U http://geodesic.mathdoc.fr/item/IM2_1969_3_3_a6/
%G en
%F IM2_1969_3_3_a6