by Peng, Rui, Wang, Ming Xin, Yang, Guo Ying
Published in Acta mathematica Sinica. English series (01.05.2010)

by 蒋良军 王悦生
Published in Journal of Shanghai University (01.12.2011)

by Bie, Qunyi, Peng, Rui
Published in Chinese annals of mathematics. Serie B (01.03.2009)