. 2013 Dec 22;2013:640723. doi: 10.1155/2013/640723
Copyright © 2013 Antonio Gómez-Outes et al.
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Figure 1.
Study identification, selection, and exclusions.