@article{DAN_1977_235_4_a1,
     author = {A. V. Bitsadze},
     title = {On the {Tricomi} problem for nonlinear equations of mixed type},
     journal = {Doklady Akademii Nauk},
     pages = {733--736},
     publisher = {mathdoc},
     volume = {235},
     number = {4},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1977_235_4_a1/}
}