@article{DE_1977_13_7_a7,
     author = {V. Kh. Froim},
     title = {A system of equations that are degenerate on the plane},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1218--1224},
     publisher = {mathdoc},
     volume = {13},
     number = {7},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1977_13_7_a7/}
}