@article{DE_1985_21_6_a20,
     author = {I. V. Gaishun and N. A. Portyanko},
     title = {Regular multidimensional differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1071--1073},
     publisher = {mathdoc},
     volume = {21},
     number = {6},
     year = {1985},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1985_21_6_a20/}
}