Cyclicity of Period Annulus of a quadratic Reversible System with degenerate Critical Point. - Haihua Liang; Jianfeng Huang 004 (Int. J. Bifurc. Chaos, 2013)

Existence of periodic orbits for planar differential systems with delay angle. - Haihua Liang; Jianfeng Huang 004; Yulin Zhao (Appl. Math. Lett., 2022)