- Correspondence to Dr Yu-Tao Xiang, Faculty of Health Sciences, University of Macau, Avenida da Universidade, Taipa, 3/F, Building E12, Macau SAR, China;
- Received February 18, 2015
- Revised March 23, 2015
- Accepted April 7, 2015
- First published April 28, 2015.
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