Mr. Gajanan H. Chavhan, Mangesh S. Deshpande, Rajesh M. Jalnekar. “A Comprehensive Investigation of Drought and Standard Precipitation Index (SPI)”. Mathematical Statistician and Engineering Applications 71, no. 4 (January 23, 2023): 10058–10068. Accessed May 6, 2024. https://www.philstat.org/index.php/MSEA/article/view/1821.