Screening for vitamin d deficiency in black americans: comparison of total, free, bioavailable 25 hydroxy vitamin d levels with parathyroid hormone levels and bone mineral density - Mckee, A.; Ribeiro, Sandra Maria Lima; Malmstrom, T.K.; Perry III, H.M.; Miller, D.K.; Farr, S.S.; Niehoff, M.L.; Albert, S.G. (Journal of Nutrition, Health and Aging, 2018)