. 2012 Dec 28;7(12):e52928. doi: 10.1371/journal.pone.0052928
© 2012 Fang 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. Map of the three surveyed cities.
