2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/132561We develop a simple tensorial contraction method to obtain analytical formula for X-ray resonant magnetic scattering. We apply the method considering first electric dipole-dipole and electric quadrupole-quadrupole scattering in the isolated atom approximation and compare the results with previous works. Then we apply the method to derive phenomenological original formulas which account also for non-spherical systems and for dipole-quadrupole mixing.typo corrections : -- P_b^{\prime} has been changed to P_b^{\prime *} -- a sign changed in formula 31Other Condensed Mattertext