@article{DE_2002_38_8_a19,
     author = {V. N. Laptinskii and V. A. Livinskaya},
     title = {A {Remark} on the {Theory} of {Periodic} {Solutions} of a {Lyapunov} {Type} {Second-Order} {Matrix} {Differential} {Equation}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1133--1134},
     publisher = {mathdoc},
     volume = {38},
     number = {8},
     year = {2002},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_2002_38_8_a19/}
}