%0 Journal Article
%A E. S. Birger
%A G. A. Kalyabin
%T Theory of Weyl circles in the case of a nonselfadjoint system of second order differential equations
%J Differencialʹnye uravneniâ
%D 1976
%P 1531-1540
%V 12
%N 9
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1976_12_9_a0/
%G ru
%F DE_1976_12_9_a0