. 2010 Jan 11;12(1):R7. doi: 10.1186/ar2906
Copyright ©2010 Barthel 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.