Xiao-Guang Yao, Florian Frommlet, Ling Zhou, Feiya Zu, Hong-Mei Wang, Zhi-Tao Yan, Wen-Li Luo, Jing Hong, Xin-Ling Wang and Nan-Fang Li*
* Corresponding author: Nan-Fang Li Lnanfang@yahoo.com.cn
BMC Public Health 2010, 10:91 doi:10.1186/1471-2458-10-91
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