@article{DAN_1969_188_6_a5,
     author = {G. D. Karatoprakliev},
     title = {A certain boundary value problem for equations of mixed type in multidimensional regions},
     journal = {Doklady Akademii Nauk},
     pages = {1223--1226},
     publisher = {mathdoc},
     volume = {188},
     number = {6},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1969_188_6_a5/}
}