Relationship of 25-Hydroxyvitamin D and Interleukin-6 with Frailty in Hospitalized Elderly Patients with Chronic Disease in the Stable Phase 
DAI Jingrong, LI Jie, HE Xu, LI Yang, LI Yan
Chinese General Practice . 2021, (36): 4599 -4606 .  DOI: 10.12114/j.issn.1007-9572.2021.02.037