Rizky, Fahmi, Sri Sudiarti, and Atika. “Strategi Costumer Relationship Management Dalam Mempertahankan Pelanggan Pada Coffee Shop Grama Sphere”. eCo-Fin 5, no. 3 (October 10, 2023): 247–259. Accessed July 22, 2024. https://jurnal.kdi.or.id/index.php/ef/article/view/951.