N. Nasirsah, F. S. H. Fatma, R. A. Siregar, E. S. Siregar, and S. Tuah, “Exploration of Salam Leaf Extract (Syzygium polyanthum) as a Natural Indicator for Acid-Base Titration: Color Stability and Endpoint Accuracy”, J. Pijar.MIPA, vol. 20, no. 7, pp. 1335–1340, Dec. 2025.