General approach to the Lagrangian ambiguity in f(R, T) gravity G. A. Carvalho, F. Rocha, H. O. Oliveira and R. V. Lobato Eur. Phys. J. C, 81 2 (2021) 134 Published online: 07 February 2021 DOI: 10.1140/epjc/s10052-021-08920-4