. 2019 Jun 2;2019:6710352. doi: 10.1155/2019/6710352
Copyright © 2019 Zhenhua Liu and Hongtai Shi.
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.
Flow diagram of the study selection process.