@article{DAN_1979_244_4_a12,
     author = {Y. P. Popov and P. D. Krut'ko},
     title = {Symmetry in automatic control systems},
     journal = {Doklady Akademii Nauk},
     pages = {842--845},
     publisher = {mathdoc},
     volume = {244},
     number = {4},
     year = {1979},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1979_244_4_a12/}
}