@article{DAN_1974_214_3_a2,
     author = {P. V. Berkhin},
     title = {On a boundary value problem for equations of composite type},
     journal = {Doklady Akademii Nauk},
     pages = {496--498},
     publisher = {mathdoc},
     volume = {214},
     number = {3},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1974_214_3_a2/}
}