%0 Journal Article %A M. I. Serov %T Certain properties of the spectrum of a non-selfadjoint differential operator of the second order %J Doklady Akademii Nauk %D 1960 %P 27-29 %V 131 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/item/DAN_1960_131_1_a5/ %G ru %F DAN_1960_131_1_a5