@article{DE_1977_13_8_a10,
     author = {V. Kh. Froim},
     title = {Some partial differential equations that are degenerate on a hyperplane},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1446--1453},
     year = {1977},
     volume = {13},
     number = {8},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1977_13_8_a10/}
}