Spinning black holes with a separable Hamilton–Jacobi equation from a modified Newman–Janis algorithmHaroldo C. D. Lima Junior, Luís C. B. Crispino, Pedro V. P. Cunha and Carlos A. R. HerdeiroEur. Phys. J. C, 80 11 (2020) 1036DOI: https://doi.org/10.1140/epjc/s10052-020-08572-w