N. H. . Din and C. S. M. . Muhammad Basri, “Modelling Vitamin D Concentration Dynamics in the Human Body Using Partial Differential Equation”, EKST, vol. 6, no. 1, pp. 281–289, Aug. 2026, Accessed: Aug. 14, 2026. [Online]. Available: https://periodical.uthm.edu.my/index.php/ekst/article/view/22444