2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/107254A model based on the local gauge group SU(3)_c x SU(3)_L x U(1)_X without particles with exotic electric charges is shown to be able to provide the quark mass spectrum and their mixing, by means of universal see-saw mechanisms, avoiding a hierarchy in the Yukawa coupling constants.7 pages, 1 eps figure. Published in Europhysics LettersHigh Energy Physics - Phenomenologytext