%0 Journal Article %A V. D. Charushnikov %T Optimal approximate methods for the solution of linear problems %J Differencialʹnye uravneniâ %D 1971 %P 344-352 %V 7 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/DE_1971_7_2_a14/ %G ru %F DE_1971_7_2_a14