%0 Journal Article
%A P. L. Ul'yanov
%A Yu. V. Pokornyi
%T Voronezh Mathematical School  ``Theory of Functions, Differential Equations in Mathematical Modelling''
%J Trudy Matematicheskogo Instituta imeni V.A. Steklova
%D 1993
%V 48
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/RM_1993_48_4_a16/
%G ru
%F RM_1993_48_4_a16