18.Jacob RA, Sotoudeh G. Vitamin C function and status in chronic disease. Nutr Clin Care. 2002 Mar-Apr;5(2):66-74. http://www.ncbi.nlm.nih.gov/pubmed/12134712?dopt=Abstract
19.Routine Vitamin Supplementation to Prevent Cancer and Cardiovascular Disease, Topic Page. June 2003. U.S. Preventive Services Task Force. http://www.uspreventiveservicestaskforce.org/uspstf/uspsvita.htm
20.Nutritive Value of Foods, United States Department of Agriculture, Agricultural Research Service, Home and Garden Bulletin Number 72. May be accessed at:
https://www.ars.usda.gov/SP2UserFiles/Place/12354500/Data/SR25/nutrlist/sr25w401.pdf
21.Carr AC, Frei B.Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans. Am J Clin Nutr. 1999 Jun;69(6):1086-107. http://www.ncbi.nlm.nih.gov/pubmed/10357726