@article{DE_1972_8_5_a7,
     author = {V. L. Novikov},
     title = {The instability of the characteristic exponents of systems of linear differential equations with almost periodic coefficients},
     journal = {Differencialʹnye uravneni\^a},
     pages = {795--800},
     publisher = {mathdoc},
     volume = {8},
     number = {5},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1972_8_5_a7/}
}