. 2004 Nov 30;3:26. doi: 10.1186/1476-511X-3-26
Copyright © 2004 Strandhagen et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Figure 1.
Study design