Association of serum 25-hydroxyvitamin D3 and D2 with academic performance in childhood: findings from a prospective birth cohort
Anna-Maija Tolppanen, Adrian Sayers, William D Fraser, Debbie A Lawlor
Journal of Epidemiology & Community Health Dec 2012, 66 (12) 1137-1142; DOI: 10.1136/jech-2011-200114