Park, Yang-Byung, and Sung-Joon Yoon. “THE OPERATION OF VENDING MACHINE SYSTEMS WITH STOCK-OUT-BASED, ONE-STAGE ITEM SUBSTITUTION”. International Journal of Industrial Engineering: Theory, Applications and Practice 19, no. 11 (February 20, 2013). Accessed April 26, 2026. https://ijietap.journals.publicknowledgeproject.org/ijietap/index.php/ijie/article/view/747.