“The Prediction of The Drought Index in The Indragiri Watershed Using SARIMA and SPI Methods”. Sainmatika: Jurnal Ilmiah Matematika dan Ilmu Pengetahuan Alam 20, no. 1 (June 30, 2023): 72–82. Accessed June 21, 2026. https://jurnal.univpgri-palembang.ac.id/index.php/sainmatika/article/view/11501.