“Analysis of Caffeine, Ash, Water and Coffee Extract Levels On Commercial Ground Coffee Samples”. ALKIMIA : Jurnal Ilmu Kimia dan Terapan 6, no. 2 (March 15, 2023): 276–284. Accessed September 19, 2024. https://jurnal.radenfatah.ac.id/index.php/alkimia/article/view/14517.