Ip, D., Lau, E. H., Tam, Y.- hung, So, T., Lam, C.- kin, Cowling, B. J. and Leung, G. M. (2015) “Evaluation of an Electronic Smart-Card Based School Absenteeism Surveillance System”, Online Journal of Public Health Informatics, 7(1). doi: 10.5210/ojphi.v7i1.5801.