Association Between Vitamin D, Frailty, and Progression of Frailty in Community-Dwelling Older Women
David Buchebner,  Patrik Bartosch, Linnea Malmgren,  Fiona E McGuigan, Paul Gerdhem,  Kristina E Akesson
The Journal of Clinical Endocrinology & Metabolism, Volume 104, Issue 12, December 2019, Pages 6139–6147,
https://doi.org/10.1210/jc.2019-00573