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@article{DE_1997_33_5_a9, author = {Yu. A. Il'in}, title = {On the asymptotic perturbation of a nonlinear center}, journal = {Differencialʹnye uravneni\^a}, pages = {632--637}, publisher = {mathdoc}, volume = {33}, number = {5}, year = {1997}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1997_33_5_a9/} }
Yu. A. Il'in. On the asymptotic perturbation of a nonlinear center. Differencialʹnye uravneniâ, Tome 33 (1997) no. 5, pp. 632-637. http://geodesic.mathdoc.fr/item/DE_1997_33_5_a9/