Yau, T O
Wu, C W
Dong, Y
Tang, C-M
Ng, S S M
Chan, F K L
Sung, J J Y
Yu, J
Article History
Received: 21 April 2014
Revised: 6 August 2014
Accepted: 8 August 2014
First Online: 18 September 2014
Competing interests
: The authors declare no conflict of interest.