%0 Journal Article
%A O. I. Nikonov
%T Some extremal properties of observable differential systems
%J Differencialʹnye uravneniâ
%D 1985
%P 236-240
%V 21
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1985_21_2_a5/
%G ru
%F DE_1985_21_2_a5