Song, Huajun
Qiu, Peihua http://orcid.org/0000-0003-4439-9466
Funding for this research was provided by:
Division of Mathematical Sciences (1405698)
National Natural Science Foundation of China (61305012)
Article History
Received: 4 March 2016
Revised: 1 September 2016
Accepted: 7 September 2016
First Online: 22 September 2016