When GRB afterglows get softer, hard components come into play A. Moretti, R. Margutti, F. Pasotti, A. P. Beardmore, S. Campana, G. Chincarini, S. Covino, O. Godet, C. Guidorzi, J. P. Osborne et al. (2 more) A&A, 478 2 (2008) 409-417 Published online: 04 December 2007 DOI: 10.1051/0004-6361:20078805