. 2012 Feb 3;12:3. doi: 10.1186/1472-6904-12-3
Copyright ©2012 Sandilands 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.
4 way study design.