Usman, I. G., M. O. Ibrahim, B. Y. Isah, N. Lawal, and S. T. Akinyemi. “APPLICATION OF NON-STANDARD FINITE DIFFERENCE METHOD ON COVID-19 MATHEMATICAL MODEL WITH FEAR OF INFECTION”. FUDMA JOURNAL OF SCIENCES, Vol. 7, no. 4, Aug. 2023, pp. 357 -68, doi:10.33003/fjs-2023-0704-1933.