Juanjuan Wu
      The cyclicity of period annuli of a quadratic reversible Lotka-Volterra system with two centers
      Nonlinear Analysis and Differential Equations, Vol. 3, 2015, no. 3, 133-142
      http://dx.doi.org/10.12988/nade.2015.524

Copyright © 2015 Juanjuan Wu. This article is distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.