by Wang, Yu-Yu (瑜玉 王), Zhao, Yong-Tao (永涛 赵), Sun, Jian-Rong (建荣 孙), Li, De-Hui (德慧 李), Li, Jin-Yu (锦钰 李), Wang, Ping-Zhi (平志 王), Xiao, Guo-Qing (国青 肖)
Published in Chinese physics letters (01.05.2011)