Shishikura also given an example:Mitsuhiro Shishikura, Surgery of complex analytic dynamical systems, in "Dynamical Systems and Nonlinear Oscillations", Ed. by Giko Ikegami, World Scientific Advanced Series in Dynamical Systems, 1, World Scientific, 1986, 93–105. a rational function which possesses a Herman ring with period 2, but the parameters showed above are different from his.
