We study a class of quasi symmetric seventh degree systems and obtain the conditions that its two singular points can be two centers at the same step by careful computing and strict proof. In addition, the condition of an isochronous center is also given. In terms of quasi symmetric systems, our work is interesting and obtained conclusions about bicenters are new.
Du Chaoxiong. "The Problem of Bicenter and Isochronicity for a Class of Quasi Symmetric Planar Systems." Abstr. Appl. Anal. 2014 (SI66) 1 - 11, 2014. https://doi.org/10.1155/2014/482450