Salisu Ibrahim, Mowafaq Muhammed Al-Kassab. “Using Linear Regression Analysis to Study the Recovery Cases of COVID 19 in Erbil, Kurdistan Region”. Drugs and Cell Therapies in Hematology, vol. 10, no. 1, Aug. 2021, pp. 1226-39, http://dcth.org/index.php/journal/article/view/243.