Ip, Dennis, Eric H.Y. Lau, Yat-hung Tam, Teresa So, Chi-kin Lam, Benjamin J. Cowling, and Gabriel M. Leung. “Evaluation of an Electronic Smart-Card Based School Absenteeism Surveillance System”. Online Journal of Public Health Informatics 7, no. 1 (February 26, 2015). Accessed January 18, 2022. https://ojphi.org/ojs/index.php/ojphi/article/view/5801.