“Optimization and Validation of Caffeine in Robusta Coffee (Coffea canephora), Black Tea (Camellia sinensis), and Cocoa (Theobroma cacao L.) Using RP-HPLC Liquid-liquid Extraction” (2026) Jurnal Farmasi Sains dan Komunitas (Journal of Pharmaceutical Sciences and Community), 23(1), pp. 114–123. doi:10.24071/jpsc.v23i1.1086.