Mayo Clinic Q and A: How much vitamin D do I need? - Mayo Clinic News Network
Taking too much vitamin D can cloud its benefits and create health risks - Harvard Health
Bronson Vitamin D3 2000 IU (1 Year Supply) for Immune Support Healthy Muscle Function & Bone Health High Potency Organic Non-GMO Vitamin D Supplement 360 Tablets
Vitamin D3 2,000 IU for Immunity – Harmonia Wellness
Ddrops Liquid Vitamin D3 Drops 2000 Iu (50 Mcg) - 180 Drops - 0.17 Fl Oz : Target