%0 Journal Article %A N. A. Lyul'ko %T The increasing smoothness property of solutions to some hyperbolic problems in two independent variables %J Sibirskie èlektronnye matematičeskie izvestiâ %D 2010 %P 413-424 %V 7 %I mathdoc %U http://geodesic.mathdoc.fr/item/SEMR_2010_7_a39/ %G en %F SEMR_2010_7_a39