Qi F, Jia X R, Li S P, Liu H, Wang Y N
Department of Health Education, Qingdao municipal Center for Disease Control and Prevention, Qingdao 266033, China.
Zhonghua Yu Fang Yi Xue Za Zhi. 2016 Jul 6;50(7):652-5. doi: 10.3760/cma.j.issn.0253-9624.2016.07.017.