%0 Journal Article
%A L. Z. Fishman
%T On the preservation of the properties of differential equations
%J Doklady Akademii Nauk
%D 1996
%P 594-596
%V 346
%N 5
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1996_346_5_a3/
%G ru
%F DAN_1996_346_5_a3