@article{DE_1988_24_1_a11,
     author = {K. Yu. Kishkis},
     title = {The index of the {Bitsadze{\textendash}Samarskiǐ} problem for harmonic functions},
     journal = {Differencialʹnye uravneni\^a},
     pages = {105--110},
     year = {1988},
     volume = {24},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1988_24_1_a11/}
}