Kutrolli, G. , Kutrolli, M. , Meco, E.. "The Origin, Diffusion and a Comparison of Ordinary Differential Equations Numerical Solutions Used by SIR Model in Order to Predict SARS-CoV-2 in Nordic Countries". World Academy of Science, Engineering and Technology, Open Science Index 169, International Journal of Medical and Health Sciences (2021), 15(1), 33 - 62.