. 2014 Jul 21;9(7):e102443. doi: 10.1371/journal.pone.0102443
© 2014 Zhu et al
This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
Figure 1. Flow diagram of included and excluded studies.
