Ainan ARSHAD, Saad Bin Zafar MAHMOOD, Ahmed AYAZ, Adil Al Karim MANJI, and Akash Kumar AHUJA, “Association of vitamin D deficiency and disease activity in systemic lupus erythematosus patients: Two-year follow-up study”, Archives of Rheumatology, vol. 36, no. 1, pp. 101–106, Mar. 2021.