A randomized trial of vitamin D(3) supplementation in children: dose-response effects on vitamin D metabolites and calcium absorption - Lewis, R D; Laing, E M; Hill Gallant, K M; Hall, D B; McCabe, G P; Hausman, D B; Martin, B R; Warden, S J; Peacock, M; Weaver, C M (J Clin Endocrinol Metab, 2013)