Assessment of serum total 25-hydroxyvitamin D assay commutability of Standard Reference Materials and College of American Pathologists Accuracy-Based Vitamin D (ABVD) Scheme and Vitamin D External Quality Assessment Scheme (DEQAS) materials: Vitamin D Standardization Program (VDSP) Commutability Study 2

Johanna E Camara, Stephen A. Wise, Andrew N. Hoofnagle, Emma L. Williams, Graham D. Carter, Julia C. Jones, Carolyn Q Burdette, Grace Hahm, Federica Nalin, Adam J. Kuszak, Joyce Merkel, Ramón Durazo-Arvizú, Pierre Lukas, Etienne Cavalier, Christian Popp, Christian Beckert, Jan Schultess, Glen Van Slooten, Carole Tourneur, Camille Pease, Ravi Kaul, Alfredo Villarreal, Fiona Ivison, Ralf Fischer, Jody M.W. van den Ouweland, Chung Shun Ho, Emmett W. K. Law, Jean-Nicolas Simard, Renaud Gonthier, Brett Holmquist, Marcelo C. Batista, Heather Pham, Alex Bennett, Sarah Meadows, Lorna Cox, Eugène Jansen, Dilshad Ahmed Khan, Kimberly Robyak, Michael H. Creer, Mark Kilbane, Patrick J. Twomey, James Freeman, Neil H. Parker, Jinyun Yuan, Robert L. Fitzgerald, Sohail Mushtaq, Michael W. Clarke, Norma Breen, Christine Simpson, Christopher T. Sempos