. 2006 Oct 31;47(5):688–697. doi: 10.3349/ymj.2006.47.5.688
Copyright © 2006 The Yonsei University College of Medicine
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.