Vitamin D3 supplementation in patients with frequent respiratory tract infections: a randomised and double-blind intervention study - Bergman, P; Norlin, A C; Hansen, S; Rekha, R S; Agerberth, B; Bjorkhem-Bergman, L; Ekstrom, L; Lindh, J D; Andersson, J (BMJ Open, 2012)
pii: e001663