%0 Journal Article
%A V. I. Bernik
%A É. I. Kovalevskaya
%T Two-dimensional extremal surfaces with jointly extremal partial derivatives
%J Matematičeskie zametki
%D 1991
%P 14-19
%V 50
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MZM_1991_50_2_a1/
%G ru
%F MZM_1991_50_2_a1