High prevalence of vitamin D inadequacy and implications for health.
Holick MF. Mayo Clin Proc. Mar 2006;81(3):353-373.

Why the optimal requirement for Vitamin D(3) is probably much higher than what is officially recommended for adults.
Vieth R. J Steroid Biochem Mol Biol. May 2004;89-90:575-579.

Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes.
Bischoff-Ferrari HA, Giovannucci E, Willett WC, Dietrich T, Dawson-Hughes B. Am J Clin Nutr. Jul 2006;84(1):18-28.

Efficacy and safety of vitamin D3 intake exceeding the lowest observed adverse effect level.
Vieth R, Chan PC, MacFarlane GD. Am J Clin Nutr. Feb 2001;73(2):288-294.

Vitamin D deficiency during pregnancy: an ongoing epidemic.
Hollis BW, Wagner CL. Am J Clin Nutr. Aug 2006;84(2):273.

The role of vitamin D for bone health and fracture prevention.
Holick MF. Curr Osteoporos Rep. Sep 2006;4(3):96-102.

Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety.
Vieth R. Am J Clin Nutr. May 1999;69(5):842-856.

Circulating 25-hydroxyvitamin D levels indicative of vitamin D sufficiency: implications for establishing a new effective dietary intake recommendation for vitamin D.
Hollis BW. J Nutr. Feb 2005;135(2):317-322.

Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol.
Heaney RP, Davies KM, Chen TC, Holick MF, Barger-Lux MJ. Am J Clin Nutr. Jan 2003;77(1):204-210.

Diagnosis and treatment of vitamin D deficiency.
Cannell JJ, Hollis BW, Zasloff M, Heaney RP. Expert Opinion on Pharmacotherapy. January 2008, Vol. 9, No. 1, 107-118