Chen, H
Huang, S
Han, X
Zhang, J
Shan, C
Tsang, Y H
Ma, H T
Poon, R Y C
Article History
Received: 3 December 2013
Revised: 2 March 2014
Accepted: 6 March 2014
First Online: 17 April 2014
Competing interests
: The authors declare no conflict of interest.