K. M. C. Ong, T. L. G. Cruz, and P. E. R. Grullo, “Prevalence and Reasons for Non-Follow-Up of Newborns with ‘Refer’ Results on Initial Hearing Screening”, Philipp J Otolaryngol Head Neck Surg, vol. 32, no. 2, pp. 17–21, Jul. 2018.