Preliminary results of an aging test of RPC chambers for the LHCb Muon System - Bizzeti, A.; Carboni, G.; Collazuol, G.; De Capua, S.; Domenici, D.; Ganis, G.; Messi, R.; Passaleva, G.; Santovetti, E.; Veltri, M. (Nuclear Instruments & Methods in Physics Research Section A, 2003)