title: Letter: Seasonal variations in serum 25-hydroxycholecalciferol.
mesh_terms: D001667:Binding, Competitive; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood*; D012621:Seasons; D013472:Sunlight; D014466:Ultraviolet Rays
chemical_list: D006887:Hydroxycholecalciferols