A study on fractional HBV model through singular and non-singular derivativesSunil Kumar, R. P. Chauhan, Ayman A. Aly, Shaher Momani and Samir HadidEur. Phys. J. Spec. Top., 231 10 (2022) 1885-1904DOI: https://doi.org/10.1140/epjs/s11734-022-00460-6