@article{DE_1982_18_3_a19,
     author = {A. G. Kuz'min},
     title = {On the behavior of characteristics of equations of mixed type with a closed line of degeneracy},
     journal = {Differencialʹnye uravneni\^a},
     pages = {533--534},
     publisher = {mathdoc},
     volume = {18},
     number = {3},
     year = {1982},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1982_18_3_a19/}
}