Ali, M. M.; Eisa, M.; Taha, M. I.; Zakaria, B. A.; Elbashir, A. A. Determination of Caffeine in Some Sudanese Beverages by High Performance Liquid Chromatography. Pak. J. Nutr. 2012, 11 (4), 336–342. https://doi.org/10.3923/pjn.2012.336.342.