Gao, J
Li, N
Dong, Y
Li, S
Xu, L
Li, X
Li, Y
Li, Z
Ng, S S
Sung, J J
Shen, L
Yu, J
Article History
Received: 21 June 2014
Revised: 24 August 2014
Accepted: 29 August 2014
First Online: 3 November 2014
Competing interests
: The authors declare no conflict of interest.