ESO, Mayuening, Metta KUNING, Hilary GREEN, Attachai UERANANTASUN, and Somporn CHUAI-AREE. “The Southern Oscillation Index As a Random Walk”. Walailak Journal of Science and Technology (WJST) 13, no. 5 (October 12, 2015): 317–327. Accessed July 11, 2026. https://wjst.wu.ac.th/index.php/wjst/article/view/1816.