@article{DAN_1991_318_4_a11,
     author = {Ya. A. Roitberg},
     title = {Boundary and mixed problems for general hyperbolic systems in a complete scale of spaces of {Sobolev} type},
     journal = {Doklady Akademii Nauk},
     pages = {820--824},
     publisher = {mathdoc},
     volume = {318},
     number = {4},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1991_318_4_a11/}
}