Cosmic microwave background polarization and reionization: Constraining models with a double reionizationL. P. L. Colombo, G. Bernardi, L. Casarini, R. Mainini, S. A. Bonometto, E. Carretti and R. FabbriA&A, 435 2 (2005) 413-420DOI: https://doi.org/10.1051/0004-6361:20041761