Hopf bifurcation for some analytic differential systems in ℝ³ via averaging theory

We study the Hopf bifurcation from the singular point with eigen-values a ε ± b i and c ε located at the origen of an analytic diffierential system of the form ẋ = f(x), where x ∈ ℝ3. Under convenient assumptions we prove that the Hopf bifurcation can produce 1, 2 or 3 limit cycles. We also characterize the stability of these limit cycles. The main tool for proving these results is the averaging theory of first and second order.