@article{DE_1965_1_3_a15,
     author = {Yu. I. Kovach},
     title = {Application of the theorem of differential inequalities to the {Goursat} problem for a linear system of partial differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {411--420},
     publisher = {mathdoc},
     volume = {1},
     number = {3},
     year = {1965},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1965_1_3_a15/}
}