@article{DE_1972_8_1_a6,
     author = {G. D. Karatoprakliev},
     title = {Equations of mixed type and degenerate hyperbolic equations in multidimensional domains},
     journal = {Differencialʹnye uravneni\^a},
     pages = {55--67},
     publisher = {mathdoc},
     volume = {8},
     number = {1},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1972_8_1_a6/}
}