%0 Journal Article %A Tunca, Gülen Başcanbaz %A Bairamov, Elgiz %T Discrete spectrum and principal functions of non-selfadjoint differential operator %J Czechoslovak Mathematical Journal %D 1999 %P 689-700 %V 49 %N 4 %I mathdoc %U http://geodesic.mathdoc.fr/item/CMJ_1999__49_4_a2/ %G en %F CMJ_1999__49_4_a2