@article{DE_1968_4_5_a5,
     author = {V. I. Chemodanov},
     title = {The isochronism of a certain system of differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {821--829},
     publisher = {mathdoc},
     volume = {4},
     number = {5},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1968_4_5_a5/}
}