Fikri, Mulya, Rizki Prakasa Hasibuan, Nelma Busra, and Dita Saraswati. “Quality Control Analysis of Products Using the Six Sigma Method: A Case Study at PT. XYZ”. Unified Systems Approach for Human centered Operations (USAHO) 1, no. 1 (August 30, 2026): 1–16. Accessed September 9, 2026. https://gpijournal.com/index.php/usaho/article/view/652.