Sihotang, D. A. H., and A. . Aprianingsih. “The Impact of a Loyalty Program on Credit Card Portfolio Performance: A Cluster-Based Analysis of Redeemers and Non-Redeemers in Q Rewards, Q-Bank Qatar”. Eduvest - Journal of Universal Studies, vol. 6, no. 1, Jan. 2026, pp. 808-25, doi:10.59188/eduvest.v6i1.51987.