Salesman, F. “The Effect of Maternal Education Level, Family Income, and Maternal Working Time to Basic Vaccine Service on 0-24 Infants in Kupang Regency, East Nusa Tenggara”. Journal of Health Policy and Management, vol. 2, no. 2, Nov. 2017, pp. 112-6, http://thejhpm.com/index.php/thejhpm/article/view/31.