Non-perturbative treatment of the linear covariant gauges by taking into account the Gribov copiesM. A. L. Capri, A. D. Pereira, R. F. Sobreiro and S. P. SorellaEur. Phys. J. C, 75 10 (2015) 479DOI: https://doi.org/10.1140/epjc/s10052-015-3707-z