Characterization of large-area photomultipliers under low magnetic fields: Design and performance of the magnetic shielding for the Double Chooz neutrino experiment - Calvo, E.; Cerrada, M.; Fernández-Bedoya, C.; Gil-Botella, I.; Palomares, C.; Rodríguez, I.; Toral, F.; Verdugo, A. (Nuclear Instruments & Methods in Physics Research Section A, 2010)