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@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/} }
V. I. Chemodanov. The isochronism of a certain system of differential equations. Differencialʹnye uravneniâ, Tome 4 (1968) no. 5, pp. 821-829. http://geodesic.mathdoc.fr/item/DE_1968_4_5_a5/