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@article{DE_1969_5_6_a10, author = {I. I. Pleshkan}, title = {A new method of research on the isochronism of a system of two differential equations}, journal = {Differencialʹnye uravneni\^a}, pages = {1083--1090}, publisher = {mathdoc}, volume = {5}, number = {6}, year = {1969}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1969_5_6_a10/} }
I. I. Pleshkan. A new method of research on the isochronism of a system of two differential equations. Differencialʹnye uravneniâ, Tome 5 (1969) no. 6, pp. 1083-1090. http://geodesic.mathdoc.fr/item/DE_1969_5_6_a10/