Zhang, Xiao-yong
Wan, Zheng-su
Funding for this research was provided by:
the National Natural Science Foundation of China (11371074,11271118,11301172, Tianyuan Fund for Mathematics, Grant No. 11426103)
the Natural Science Foundation of Hunan Province (13JJ4095)
the Construct Program of the Key Discipline in Hunan Province and the Key Foundation of Hunan Provincial Education Department (11A043)