@article{DE_1980_16_2_a4,
     author = {S. A. Grishin and V. I. Utkin},
     title = {On extending the definition of discontinuous systems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {227--235},
     publisher = {mathdoc},
     volume = {16},
     number = {2},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1980_16_2_a4/}
}