%0 Journal Article %A G. S. Zhukova %T Minimal smoothness of coefficients in the construction of approximate solutions %J Izvestiâ vysših učebnyh zavedenij. Matematika %D 1988 %P 63-67 %N 12 %I mathdoc %U http://geodesic.mathdoc.fr/item/IVM_1988_12_a11/ %G ru %F IVM_1988_12_a11