Analytical Performance Specifications for 25-Hydroxyvitamin D Examinations oleh Etienne Cavalier, Callum G. Fraser, Harjit P. Bhattoa, Annemieke C. Heijboer, Konstantinos Makris, Candice Z. Ulmer, Hubert W. Vesper, Samuel Vasikaran, Pierre Lukas, Pierre Delanaye, Anna Carobene, on behalf of the IFCC-IOF Committee for Bone Metabolism