%0 Journal Article
%A V. A. Yakubovich
%T A frequency theorem for periodic systems
%J Doklady Akademii Nauk
%D 1986
%P 70-73
%V 287
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1986_287_1_a15/
%G ru
%F DAN_1986_287_1_a15