. 2013 Jul 26;9:29. doi: 10.1186/1744-8603-9-29
Copyright © 2013 Robert and Ridde; 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 2.
Selection process of the documents.