Gorton, HC; Jarvis, K. (1999). „The effectiveness of vitamin C in preventing and relieving the symptoms of virus-induced respiratory infections.”. Journal of Manipulative and Physiological Therapeutics. 22 (8): 530—3. PMID10543583. doi:10.1016/s0161-4754(99)70005-9.
Gorton, HC; Jarvis, K. (1999). „The effectiveness of vitamin C in preventing and relieving the symptoms of virus-induced respiratory infections.”. Journal of Manipulative and Physiological Therapeutics. 22 (8): 530—3. PMID10543583. doi:10.1016/s0161-4754(99)70005-9.