1. Ruxton, C. H. (2008). The impact of caffeine on mood, cognitive function, performance and hydration: a review of benefits and risks. Nutrition Bulletin33(1), 15-25. 
  2. Verster, J. C., & Koenig, J. (2018). Caffeine intake and its sources: A review of national representative studies. Critical Reviews in Food Science and Nutrition58(8), 1250-1259. 
  3. Fitt, E., Pell, D., & Cole, D. (2013). Assessing caffeine intake in the United Kingdom diet. Food chemistry140(3), 421-426. 
  4. Nehlig, A. (2010). Is caffeine a cognitive enhancer?. Journal of Alzheimer’s Disease20(s1), S85-S94. 
  5. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). (2015). Scientific Opinion on the safety of caffeine. EFSA Journal13(5), 4102. 
  6. Van Soeren, M. H., & Graham, T. E. (1998). Effect of caffeine on metabolism, exercise endurance, and catecholamine responses after withdrawal. Journal of Applied Physiology85(4), 1493-1501