%0 Journal Article %A A. M. Nakhushev %T Methods of stating well-posed problems for second order linear hyperbolic equations on the plane %J Differencialʹnye uravneniâ %D 1970 %P 192-195 %V 6 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/item/DE_1970_6_1_a19/ %G ru %F DE_1970_6_1_a19