F. A. Azizan, N. Roslan, R. Ruslan, A. A. Aznan, and A. Z. Mohamed Yusoff, “Soil NPK Variability Mapping for Harumanis Mango Grown in Greenhouse at Perlis, Malaysia”, Int. J. Adv. Sci. Eng. Inf. Technol., vol. 9, no. 2, pp. 495–501, Mar. 2019.