%0 Journal Article
%A N. N. Krasovskii
%T On periodical solutions of differential equations involving a time lag
%J Doklady Akademii Nauk
%D 1957
%P 252-255
%V 114
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1957_114_2_a4/
%G ru
%F DAN_1957_114_2_a4