Serum 25-hydroxyvitamin D status of the US population: 1988-1994 compared with 2000-2004.
Am J Clin Nutr. 2008 Dec;88(6):1519-27. doi: 10.3945/ajcn.2008.26182.
Am J Clin Nutr. 2008.
PMID: 19064511
Free PMC article.