Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DAN_1968_182_4_a7, author = {I. I. Pleshkan}, title = {A new method of investigation on the isochronism of a system of differential equations}, journal = {Doklady Akademii Nauk}, pages = {768--771}, publisher = {mathdoc}, volume = {182}, number = {4}, year = {1968}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1968_182_4_a7/} }
I. I. Pleshkan. A new method of investigation on the isochronism of a system of differential equations. Doklady Akademii Nauk, Tome 182 (1968) no. 4, pp. 768-771. http://geodesic.mathdoc.fr/item/DAN_1968_182_4_a7/