@article{DAN_1973_210_4_a8,
     author = {M. M. Simkin},
     title = {Criterium of proximity of impulse- and continuous systems},
     journal = {Doklady Akademii Nauk},
     pages = {783--786},
     publisher = {mathdoc},
     volume = {210},
     number = {4},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_210_4_a8/}
}