Critical behavior of AdS Gauss–Bonnet massive black holes in the presence of external string cloudHadi Ranjbari, Mehdi Sadeghi, M. Ghanaatian and Gh. ForozaniEur. Phys. J. C, 80 1 (2020) 17DOI: https://doi.org/10.1140/epjc/s10052-019-7592-8