Fondell E, Balter O, Rothman KJ. Dietary intake and supplement use of vitamins C and E and upper respiratory tract infection. J Am Coll Nutr. 2011 Aug 1;30(4):248-58.
Derby CA, Araujo AB, Johannes CB, Feldman HA, McKinlay JB. Measurement of erectile dysfunction in population-based studies: the use of a single question self-assessment in the Massachusetts Male Aging Study. Int J Impot Res. 2000 Aug 1;12(4):197-204.