- Correspondence to Moo-Song Lee, Department of Clinical Epidemiology and Biostatistics, Department of Preventive Medicine, Asan Medical Center, University of Ulsan College of Medicine, 43-gil Olympic-ro, Songpa-gu, Seoul 138-736, Korea; ,
- Received July 9, 2013
- Revised January 3, 2014
- Accepted January 9, 2014
- First published January 31, 2014.
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