@article{DE_1990_26_8_a15,
     author = {R. S. Khairullin},
     title = {The {Tricomi} problem for an equation of mixed type of the second kind in the case of a normal domain},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1396--1407},
     publisher = {mathdoc},
     volume = {26},
     number = {8},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1990_26_8_a15/}
}