- Correspondence to Professor Xiubo Jiang, Department of Epidemiology and Health Statistics, The School of Public Health of Qingdao University, Qingdao 266021, China;
- Received March 26, 2018
- Revised May 23, 2018
- Accepted May 28, 2018
- First published June 15, 2018.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.