%0 Journal Article %A A. A. Zlotnik %A I. D. Turetaev %T Sharp error estimates of some two-level methods of solving the three-dimensional heat equation %J Sbornik. Mathematics %D 1987 %P 529-544 %V 56 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/SM_1987_56_2_a14/ %G en %F SM_1987_56_2_a14