@article{DE_1990_26_2_a19,
     author = {E. E. Barbashina},
     title = {Necessary conditions with matrix impulses for a {Goursat{\textendash}Darboux} system},
     journal = {Differencialʹnye uravneni\^a},
     pages = {342--343},
     year = {1990},
     volume = {26},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1990_26_2_a19/}
}