Utami, Indrianti Putri. “Praktik Jual Beli Pre Order Dengan Sistem Online: Practice of Pre-Order Buying and Selling With Online System”. Al-Muamalat: Jurnal Ekonomi Syariah 9, no. 1 (August 4, 2022): 20–28. Accessed June 16, 2025. http://103.55.33.27/index.php/mua/article/view/14045.