Wafia, Nur Umaima, Reni Furwanti, and Dini Maulana Lestari. “Immaterial Cost and Production: Maximum Production Cost Level Through Marginal Approach”. el-Jizya : Jurnal Ekonomi Islam 8, no. 2 (November 27, 2020): 128–149. Accessed July 3, 2025. https://ejournal.uinsaizu.ac.id/index.php/eljizya/article/view/4241.