2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/69620We give an elementary proof of the fact that any orientable 3-manifold admits a framing (i.e. is parallelizable) and any non-orientable 3-manifold admits a projective framing. The proof uses only basic facts about immersions of surfaces in 3-space.Geometric Topologytext