Alzami, Farrikh, Erika Devi Udayanti, Dwi Puji Prabowo, and Rama Aria Megantara. “Document Preprocessing With TF-IDF to Improve the Polarity Classification Performance of Unstructured Sentiment Analysis”. Kinetik: Game Technology, Information System, Computer Network, Computing, Electronics, and Control 5, no. 3 (August 27, 2020): 235-242. Accessed June 20, 2021. https://kinetik.umm.ac.id/index.php/kinetik/article/view/1066.