%0 Journal Article %A V. S. Ryaben'kii %T Certain problems of the theory of difference boundary value problems %J Matematičeskie zametki %D 1970 %P 655-663 %V 7 %N 5 %I mathdoc %U http://geodesic.mathdoc.fr/item/MZM_1970_7_5_a13/ %G ru %F MZM_1970_7_5_a13