Thaibil Anwar, et al. “COST EFFECTIVE APPROACH: OPTIMAL CONTROL APPLICATION IN NARCOTICS ABUSE MODEL BY INVOLVING THE NUMBER OF DEATHS”. International Journal of Economic, Business, Accounting, Agriculture Management and Sharia Administration (IJEBAS), vol. 6, no. 3, June 2026, pp. 1519-31, https://radjapublika.com/index.php/IJEBAS/article/view/5908.