@article{DE_1987_23_1_a9,
     author = {M. G. Karatopraklieva},
     title = {On the theory of equations of mixed type with discontinuous coefficients. {I}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {85--102},
     publisher = {mathdoc},
     volume = {23},
     number = {1},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1987_23_1_a9/}
}