Yulianto, Tony, Faisol Faisol, Fatimatus Zahroh, Sri Suryanti, and Mohamad Tafrikan. “Forecasting the Recovery of COVID-19 Patients in East Java Using the Fuzzy Time Series Cheng Method”. Journal of Natural Sciences and Mathematics Research 7, no. 1 (June 30, 2021): 44–50. Accessed June 7, 2025. https://journal.walisongo.ac.id/index.php/JNSMR/article/view/11289.