@article{DE_2001_37_4_a16,
     author = {M. T. Terekhin and N. V. Retyunskikh},
     title = {Periodic {Solutions} of {Nonlinear} {Nonautonomous} {Systems} of {Ordinary} {Differential} {Equations}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {566--569},
     publisher = {mathdoc},
     volume = {37},
     number = {4},
     year = {2001},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_2001_37_4_a16/}
}