%0 Journal Article %A S. G. Krein %T Fifth Voronezh Winter Mathematical School %J Trudy Matematicheskogo Instituta imeni V.A. Steklova %D 1971 %V 26 %N 5 %I mathdoc %U http://geodesic.mathdoc.fr/item/RM_1971_26_5_a20/ %G ru %F RM_1971_26_5_a20