- Correspondence to Dr Xuedong Zhang, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, You Yi Road, Yu Zhong District, Chongqing 400016, People's Republic of China;
- Received June 18, 2014
- Revised October 11, 2014
- Accepted October 13, 2014
- First published October 29, 2014.
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