%0 Journal Article
%A Ibrahim, Sobhy El-sayed
%T The spectra of general differential operators in the direct sum spaces
%J Czechoslovak Mathematical Journal
%D 2004
%P 9-29
%V 54
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/item/CMJ_2004__54_1_a1/
%G en
%F CMJ_2004__54_1_a1