Le DPC, Nguyen NT, Nguyen XT, Bui MQ. An E-Commerce Web Simulation System (UPT-Shopping): Integrating PayPal and Chatbot-AI to Support Users in Payment and Quick Response. The UPT Journal of Science. 2025;3(3):32-40. Accessed January 21, 2026. https://tapchikhoahocupt.vn/index.php/uptjs/article/view/uptjs-56-2025