%0 Journal Article %A I. M. Petrushko %T Boundary value problems for equations of mixed type %J Trudy Matematicheskogo Instituta imeni V.A. Steklova %D 1968 %P 181-200 %V 103 %I mathdoc %U http://geodesic.mathdoc.fr/item/TM_1968_103_a11/ %G ru %F TM_1968_103_a11