2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/182653We briefly sketch the methods for a numerically stable evaluation of tensor one-loop integrals that have been used in the calculation of the complete electroweak one-loop corrections to $\Pep\Pem\to4 $fermions. In particular, the improvement of the new methods over the conventional Passarino--Veltman reduction is illustrated for some 4-point integrals in the delicate limits of small Gram (and other kinematical) determinants.5 pages, latex, 2 postscript figures, to appear in the proceedings of the "7th International Symposium on Radiative Corrections (RADCOR2005)", Shonan Village, 2005High Energy Physics - Phenomenologytext