@article{DAN_1973_208_6_a14,
     author = {V. S. Chunaev},
     title = {Switching functions},
     journal = {Doklady Akademii Nauk},
     pages = {1311--1314},
     year = {1973},
     volume = {208},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_208_6_a14/}
}