@article{DE_1976_12_1_a16,
     author = {M. M. Khachev},
     title = {The {Dirichlet} problem for a certain equation of mixed type},
     journal = {Differencialʹnye uravneni\^a},
     pages = {137--143},
     publisher = {mathdoc},
     volume = {12},
     number = {1},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1976_12_1_a16/}
}