SN Ib 1990I: Clumping and dust in the ejecta? A. Elmhamdi, I. J. Danziger, E. Cappellaro, M. Della Valle, C. Gouiffes, M. M. Phillips and M. Turatto A&A, 426 3 (2004) 963-977 Published online: 18 October 2004 DOI: 10.1051/0004-6361:20041318