Factors associated with vitamin D levels in Mongolian patients with multiple sclerosis - Myadagmaa Jaalkhorol; Amarsaikhan Dashtseren; Gantuya Magnaibayar; Badrangui Bat-Orgil; Ikuo Tsunoda; Shiirevnyamba Avirmed; Stefania Iaquinto; Viktor von Wyl (PLoS ONE, 2025)