F. A. Adumashi, K. O. Obohwemu, G. O. Abayomi, I. O. Kenneth, C. E. Ekwuluo, and F. Ituah, “Immunisation in the 21st Century: Foundations, Challenges, and Strategic Directions for Global Health”, ASSRJ, vol. 13, no. 02, pp. 107–124, Feb. 2026.