@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}, publisher = {mathdoc}, volume = {20}, number = {5}, year = {1984}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1984_20_5_a18/} }