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@article{DE_1992_28_4_a2, author = {E. V. Voskresenskii}, title = {Periodic solutions of nonlinear systems and the comparison method}, journal = {Differencialʹnye uravneni\^a}, pages = {571--576}, publisher = {mathdoc}, volume = {28}, number = {4}, year = {1992}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1992_28_4_a2/} }
E. V. Voskresenskii. Periodic solutions of nonlinear systems and the comparison method. Differencialʹnye uravneniâ, Tome 28 (1992) no. 4, pp. 571-576. http://geodesic.mathdoc.fr/item/DE_1992_28_4_a2/