%0 Journal Article %A V. V. Arestov %T Best approximation ol unbounded operators invariant with respect to a~shift by the linear bounded operators %J Informatics and Automation %D 1992 %P 3-20 %V 198 %I mathdoc %U http://geodesic.mathdoc.fr/item/TRSPY_1992_198_a0/ %G ru %F TRSPY_1992_198_a0