Ali, Mei Musa, Mawahib Eisa, Mohammed Idrees Taha, Badawi Ahmed Zakaria, and Abdalla Ahmed Elbashir. 2012. “Determination of Caffeine in Some Sudanese Beverages by High Performance Liquid Chromatography”. Pakistan Journal of Nutrition 11 (4): 336–342. https://doi.org/10.3923/pjn.2012.336.342.