@article{DE_1969_5_1_a6,
     author = {V. Kh. Froim},
     title = {Regular matrix partial differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {100--107},
     publisher = {mathdoc},
     volume = {5},
     number = {1},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1969_5_1_a6/}
}