@article{DAN_1976_230_4_a4,
     author = {G. D. Karatoprakliev},
     title = {On a class of equations of mixed type in multidimensional domains},
     journal = {Doklady Akademii Nauk},
     pages = {769--772},
     publisher = {mathdoc},
     volume = {230},
     number = {4},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1976_230_4_a4/}
}