@article{DAN_1957_112_2_a19,
     author = {G. M. Ulanov},
     title = {Invariance up to~$\varepsilon$ in linear combined automatically controlled systems},
     journal = {Doklady Akademii Nauk},
     pages = {253--256},
     publisher = {mathdoc},
     volume = {112},
     number = {2},
     year = {1957},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1957_112_2_a19/}
}