Handam, A. H., A. A. Freihat, and M. Zurigat. “The Multi-Step Homotopy Analysis Method for Solving Fractional-Order Model for HIV Infection of CD4+T Cells”. Proyecciones (Antofagasta, On Line), vol. 34, no. 4, 1, pp. 307-22, doi:10.4067/S0716-09172015000400001.