@article{DE_1989_25_1_a6,
     author = {N. Yu. Kapustin},
     title = {$L_2$-solvability of boundary value problems for equations of mixed type},
     journal = {Differencialʹnye uravneni\^a},
     pages = {50--59},
     publisher = {mathdoc},
     volume = {25},
     number = {1},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1989_25_1_a6/}
}