Manullang, F. S., A. Adnan, and D. Munir. “Factors Affecting Presbycusis on Audiogram Overview at H. Adam Malik General Hospital Medan”. Journal of Epidemiology and Public Health, vol. 6, no. 1, July 2021, pp. 12-20, https://jepublichealth.com/index.php/jepublichealth/article/view/362.