Contrasting behaviour of acoustic modes in network and non-network glassesA. Matic, L. Börjesson, G. Ruocco, C. Masciovecchio, A. Mermet, F. Sette and R. VerbeniEurophys. Lett., 54 1 (2001) 77-83DOI: https://doi.org/10.1209/epl/i2001-00231-y