New classes of anisotropic models with generalized polytropic equation of stateS. A. Mardan, I. Noureen, M. Azam, M. A. Rehman and M. HussanEur. Phys. J. C, 78 6 (2018) 516DOI: https://doi.org/10.1140/epjc/s10052-018-5992-9