2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/158452This paper has been withdrawn since its content is included in the more general version arXiv:0804.1882This paper has been withdrawn since its content is included in the more general version arXiv:0804.1882General Relativity and Quantum CosmologySharp bounds on the critical stability radius for relativistic charged spheres: Itext