. 2014 Aug 13;9(8):e104274. doi: 10.1371/journal.pone.0104274
© 2014 Qin 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. The PRISMA flowchart of literature review.
