%0 Journal Article
%A E. A. Livshitz
%T On duality principles for the problem of periodic solutions of higher order differential equations
%J Doklady Akademii Nauk
%D 1965
%P 277-280
%V 165
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1965_165_2_a7/
%G ru
%F DAN_1965_165_2_a7