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@article{DE_1977_13_5_a18, author = {A. E. Gel'man}, title = {A method of finding periodic solutions of autonomous systems of differential equations}, journal = {Differencialʹnye uravneni\^a}, pages = {949--950}, publisher = {mathdoc}, volume = {13}, number = {5}, year = {1977}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1977_13_5_a18/} }
A. E. Gel'man. A method of finding periodic solutions of autonomous systems of differential equations. Differencialʹnye uravneniâ, Tome 13 (1977) no. 5, pp. 949-950. http://geodesic.mathdoc.fr/item/DE_1977_13_5_a18/