Vass C, Gray E, Payne K. Discrete choice experiments of pharmacy services: a systematic review. Int J Clin Phar. 2016 Jun;38(3):620-30. doi: 10.1007/s11096-015-0221-1
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.