Wang, S
Dong, Y
Zhang, Y
Wang, X
Xu, L
Yang, S
Li, X
Dong, H
Xu, L
Su, L
Ng, S S M
Chang, Z
Sung, J J
Zhang, X
Yu, J
Article History
Received: 4 December 2013
Revised: 12 May 2014
Accepted: 6 June 2014
First Online: 14 July 2014
Competing interests
: The authors declare no conflict of interest.