Pasaribu, Udjianna S., et al. “Generalized Space-Time Autoregressive Modeling of the Vertical Distribution of Copper and Gold Grades With a Porphyry-Deposit Case Study”. International Journal on Advanced Science, Engineering and Information Technology, vol. 12, no. 5, Oct. 2022, pp. 2030-8, doi:10.18517/ijaseit.12.5.14835.