- van der Merwe PJ, Muller FR, Muller FO: Caffeine in sport. Urinary excretion of caffeine in healthy volunteers after intake of common caffeine-containing beverages. S Afr Med J. 1988 Aug 20;74(4):163-4. [PubMed:3406872 ]
- van der Merwe PJ, Muller FR, Muller FO: Caffeine in sport. Urinary excretion of caffeine in healthy volunteers after intake of common caffeine-containing beverages. S Afr Med J. 1988 Aug 20;74(4):163-4. [PubMed:3406872 ]