Han, Hui, Zhiqiang Fang, Xiangguang Ye, Hailei Wu, Feng Zuo, Quan Shi, Jinping Mu, and Baoliang Xu. “Seroprevalence of Antibodies for Pertussis and Diphtheria Among People Leaving or Entering China: A Cross-Sectional Study”. The Journal of Infection in Developing Countries 13, no. 05 (May 31, 2019): 394-399. Accessed May 26, 2022. https://jidc.org/index.php/journal/article/view/32053508.