F. M. Elfasakhany, M. S. Alqahtani, A. F. Elfasakhany, and A. M. A. Elguindy, “Assessment of Interleukin-21 Gene Polymorphisms and Protein Level in Rheumatoid Arthritis among Egyptians”, Open Access Maced J Med Sci, vol. 13, no. 1, pp. 55–60, Mar. 2025.