%0 Journal Article %A S. P. Novikov %T Algebraic properties of two-dimensional difference operators %J Trudy Matematicheskogo Instituta imeni V.A. Steklova %D 1997 %P 226-227 %V 52 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/item/RM_1997_52_1_a6/ %G en %F RM_1997_52_1_a6