@article{DE_1984_20_5_a18,
     author = {M. E. Kostyukovich},
     title = {Nonlinear systems of second-order differential equations with special right-hand sides},
     journal = {Differencialʹnye uravneni\^a},
     pages = {879--882},
     year = {1984},
     volume = {20},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1984_20_5_a18/}
}