%0 Journal Article %A B. G. Gabdulkhaev %T Approximate numbers of linear operators and optimization of approximate methods for solving functional equations %J Konstruktivnaya Teoriya Funktsii i Funktsional'nyi Analiz %D 1985 %P 15-26 %I mathdoc %U http://geodesic.mathdoc.fr/item/KUKTF_1985_a1/ %G ru %F KUKTF_1985_a1