Habib Syahputra Banurea, Beni Satria, and Solly Aryza. “A Design Of Prepaid Electricity Credit Recharge System Based On Dual Tone Multiple Frequency”. Jurnal Scientia 13, no. 03 (August 1, 2024): 548-563. Accessed August 25, 2025. https://www.infor.seaninstitute.org/index.php/pendidikan/article/view/2529.