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@article{DE_1971_7_2_a4, author = {I. A. Konovalov}, title = {Certain sufficient tests for the existence of limit cycles of a certain dynamic system}, journal = {Differencialʹnye uravneni\^a}, pages = {226--231}, publisher = {mathdoc}, volume = {7}, number = {2}, year = {1971}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1971_7_2_a4/} }
I. A. Konovalov. Certain sufficient tests for the existence of limit cycles of a certain dynamic system. Differencialʹnye uravneniâ, Tome 7 (1971) no. 2, pp. 226-231. http://geodesic.mathdoc.fr/item/DE_1971_7_2_a4/