Do Minh, Hoang, and Nam Tran Hoai. “Referral Reward Program Influence on Customer Engagement: The Role of Reward Type and Task Complexity”. Golden Ratio of Marketing and Applied Psychology of Business 6, no. 2 (February 7, 2026): 335–352. Accessed February 28, 2026. https://www.goldenratio.id/index.php/grmapb/article/view/1807.