@article{DE_1983_19_2_a18,
     author = {Yu. Knezhevich},
     title = {Construction of periodic solutions of ordinary differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {362--364},
     publisher = {mathdoc},
     volume = {19},
     number = {2},
     year = {1983},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1983_19_2_a18/}
}