New models of charged anisotropic polytropes with radiation density S. A. Mardan, A. A. Siddiqui, I. Noureen and R. N. Jamil Eur. Phys. J. Plus, 135 1 (2020) 3 Published online: 07 January 2020 DOI: 10.1140/epjp/s13360-019-00077-0