@article{DAN_1978_239_2_a0,
     author = {G. D. Karatoprakliev},
     title = {On the statement and solvability of boundary value problems for equations of mixed type in multidimensional domains},
     journal = {Doklady Akademii Nauk},
     pages = {257--260},
     publisher = {mathdoc},
     volume = {239},
     number = {2},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1978_239_2_a0/}
}