@article{DE_1982_18_6_a20,
     author = {N. Yu. Kapustin},
     title = {On the theory of equations of mixed type},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1078--1080},
     publisher = {mathdoc},
     volume = {18},
     number = {6},
     year = {1982},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1982_18_6_a20/}
}