TI - A study on the estimation of COVID-19 case with the adaptive kalman filter (AKF) in USA, Germany, United Kingdom, Italy, France, Russia, Brazil, India, Turkey, Spain, Peru, Colombia, South Africa, Argentina, Iran, Pakistan AU - Ă–ZBEK, L. SO - Sigma Journal of Engineering and Natural Sciences 2022;40:323-343. DO - 10.14744/sigma.2022.00036