Bogdanov, R. "Bifurcations of a Limit Cycle for a Family of Vector Fields on the Plane." Selecta Math. Soviet1, 373-388,
1981.Kuznetsov, Y. A. Elements
of Applied Bifurcation Theory. New York: Springer-Verlag, 1995.Takens,
F. "Forced Oscillations and Bifurcations." Comm. Math. Inst. Rijksuniv.
Utrecht2, 1-111, 1974.
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