R. Asra, F. K. Harefa, Z. Zulharmita, and N. Nessa, “DETERMINATION OF CALCIUM AND IRON METAL IN KELOR LEAF (Moringa oleifera Lam) by Using ATOMIC ABSORPTION SPECTROPHOTOMETRY”, journal-jps.com, vol. 1, no. 1, pp. 32-38, Feb. 2019.