Absolute acoustic band gap in coupled multilayer structuresD. Bria, B. Djafari-Rouhani, A. Bousfia, E. H. El Boudouti and A. NougaouiEurophys. Lett., 55 6 (2001) 841-846DOI: https://doi.org/10.1209/epl/i2001-00357-4