@article{DE_1984_20_5_a25,
     author = {A. S. Sumbatov},
     title = {Nonextremality of families of curves defined by dynamic equations of nonholonomic {Chaplygin} systems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {897--899},
     publisher = {mathdoc},
     volume = {20},
     number = {5},
     year = {1984},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1984_20_5_a25/}
}