@article{DAN_1971_201_2_a6,
     author = {V. V. Velichenko},
     title = {Problems of the invariance of discrete systems},
     journal = {Doklady Akademii Nauk},
     pages = {284--287},
     publisher = {mathdoc},
     volume = {201},
     number = {2},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1971_201_2_a6/}
}