%0 Journal Article
%A El-sayed Ibrahim, Sobhy
%T The General Differential Operators Generated by a Quasi-Differential Expressions with their Interior Singular Points
%J Serdica Mathematical Journal
%D 1999
%P 207-240
%V 25
%N 3
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SMJ2_1999_25_3_a2/
%G en
%F SMJ2_1999_25_3_a2