%0 Journal Article
%A V. I. Plotnikov
%T On the differentiability of the solutions of variation problems in a non-parametric form
%J Doklady Akademii Nauk
%D 1957
%P 746-749
%V 116
%N 5
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1957_116_5_a7/
%G ru
%F DAN_1957_116_5_a7