@article{DE_1993_29_5_a16,
     author = {T. Sh. Kal'menov and M. A. Sadybekov and N. E. Erzhanov},
     title = {A criterion for the strong solvability of the {Tricomi} problem for the {Lavrent'ev--Bitsadze} equation. {The} general case},
     journal = {Differencialʹnye uravneni\^a},
     pages = {870--875},
     publisher = {mathdoc},
     volume = {29},
     number = {5},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1993_29_5_a16/}
}