%0 Journal Article
%A Yu. B. Orochko
%T Impenetrability condition for a degenerate point of a one-term symmetric differential operator of even order
%J Sbornik. Mathematics
%D 2003
%P 745-774
%V 194
%N 5
%U http://geodesic.mathdoc.fr/item/SM_2003_194_5_a4/
%G en
%F SM_2003_194_5_a4