%0 Journal Article %A A. M. Kagan %T Sufficient systems %J Trudy Matematicheskogo Instituta imeni V.A. Steklova %D 1965 %P 17-23 %V 79 %I mathdoc %U http://geodesic.mathdoc.fr/item/TM_1965_79_a3/ %G ru %F TM_1965_79_a3