Sari E, Widyasari R. Application of Hotelling T2 Control Diagram to Analyze Drinking Water Quality Control at Perumda Tirtauli Pematang Siantar City. Mathline [Internet]. 2024 Feb. 17 [cited 2026 Feb. 7];9(1):273-84. Available from: http://mathline.unwir.ac.id/index.php/Mathline/article/view/578