%0 Journal Article
%A O. A. Timoshin
%T The best approximation to the operator of the second mixed derivative
%J Izvestiya. Mathematics 
%D 1998
%P 191-200
%V 62
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/item/IM2_1998_62_1_a5/
%G en
%F IM2_1998_62_1_a5