@article{DE_1982_18_1_a20,
     author = {N. G. Sorokina},
     title = {Boundary value problems for a three-dimensional equation of mixed type of the second kind},
     journal = {Differencialʹnye uravneni\^a},
     pages = {173--176},
     publisher = {mathdoc},
     volume = {18},
     number = {1},
     year = {1982},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1982_18_1_a20/}
}