M-polynomial and neighborhood M-polynomial methods for topological indices of porous graphene M. C. Shanmukha, A. Usha, K. C. Shilpa and N. S. Basavarajappa Eur. Phys. J. Plus, 136 10 (2021) 1089 Published online: 29 October 2021 DOI: 10.1140/epjp/s13360-021-02074-8