@article{DAN_1975_223_1_a13,
     author = {V. L. Azarov and L. N. Lupichev and G. A. Tavrizov},
     title = {A theorem in the perturbation theory of linear operators and its applications in the theory of linear dynamic systems},
     journal = {Doklady Akademii Nauk},
     pages = {56--59},
     publisher = {mathdoc},
     volume = {223},
     number = {1},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1975_223_1_a13/}
}