@article{DE_1970_6_1_a9,
     author = {M. M. Zainulabidov},
     title = {A boundary value problem for equations of mixed type with two intersecting curves of degeneracy},
     journal = {Differencialʹnye uravneni\^a},
     pages = {99--108},
     publisher = {mathdoc},
     volume = {6},
     number = {1},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1970_6_1_a9/}
}