Phonons in colloidal crystals R. S. Penciu, M. Kafesaki, G. Fytas, E. N. Economou, W. Steffen, A. Hollingsworth and W. B. Russel Europhys. Lett., 58 5 (2002) 699-704 Published online: 01 May 2002 DOI: 10.1209/epl/i2002-00322-3