@article{DE_1969_5_4_a13,
     author = {V. M. Millionshchikov},
     title = {The instability of the singular exponents and the non-symmetry of the relation of reducibility of linear systems of differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {749--750},
     publisher = {mathdoc},
     volume = {5},
     number = {4},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1969_5_4_a13/}
}