- Correspondence to Dr Yihua Xu, Department of Epidemiology and Biostatistics, Ministry of Education (MOE) Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China;
- Received May 13, 2017
- Revised November 28, 2017
- Accepted January 6, 2018
- First published January 19, 2018.
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