2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/145658The backbone of double bars is made out of double-frequency orbits, and loops, their maps, indicate the bars' extent, morphology and dynamics.2 pages, 1 figure; to appear in "Formation and Evolution of Galaxy Disks", ASP Conf. Ser., eds. J.G. Funes & E.M. CorsiniAstrophysicstext