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@article{DE_1967_3_12_a5, author = {\`E. V. Vdovina}, title = {Some theorems on limit cycles}, journal = {Differencialʹnye uravneni\^a}, pages = {2053--2057}, publisher = {mathdoc}, volume = {3}, number = {12}, year = {1967}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1967_3_12_a5/} }
È. V. Vdovina. Some theorems on limit cycles. Differencialʹnye uravneniâ, Tome 3 (1967) no. 12, pp. 2053-2057. http://geodesic.mathdoc.fr/item/DE_1967_3_12_a5/