Quasinormal modes and their anomalous behavior for black holes in f(R) gravityAlmendra Aragón, P. A. González, Eleftherios Papantonopoulos and Yerko VásquezEur. Phys. J. C, 81 5 (2021) 407DOI: https://doi.org/10.1140/epjc/s10052-021-09193-7