Ellynia, Ellynia, and Viany Tjhin. “Penerapan Customer Relationship Management (CRM) Pada Aplikasi Pengiriman Pesan Instan Studi Kasus: WhatsApp, WeChat, Line, KakaoTalk”. Ultima InfoSys : Jurnal Ilmu Sistem Informasi 5, no. 1 (June 30, 2014): 20-26. Accessed April 20, 2024. https://ejournals.umn.ac.id/index.php/SI/article/view/215.