@article{DE_1990_26_12_a19,
     author = {A. K. Demenchuk},
     title = {Periodic solutions of differential systems whose period is incommensurable with the period of the system itself},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2167--2170},
     publisher = {mathdoc},
     volume = {26},
     number = {12},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1990_26_12_a19/}
}