Timoer, Seindy Arya Kusuma, Bhisma Murti, and RB Soemanto. 2016. “Factor Analysis With Health Belief Model on the Adherence to Methadone Maintenance Therapy”. Journal of Epidemiology and Public Health 1 (1):49-57. https://jepublichealth.com/index.php/jepublichealth/article/view/9.