Dewi, Siti Herlina, Sri Haryani, and Triastuti Sulistyaningsih. “Chemistry Practicum Learning During the Covid-19 Pandemic: Determining the PH Scale of Acid-Base Natural Indicators With Semi-Quantitative Analysis Using Spectrum Color Measure Software”. Proceedings of International Conference on Science, Education, and Technology 7, no. 1 (March 1, 2023): 551–557. Accessed July 26, 2025. https://proceeding.unnes.ac.id/ISET/article/view/2013.