Negative group velocity in solidsTamm, Kert; Peets, Tanel; Engelbrecht, Jüri; Kartofelev, DmitriWave motion2017 / p. 127-138 : ill https://doi.org/10.1016/j.wavemoti.2016.04.010 Journal metrics at Scopus Article at Scopus Journal metrics at WOS Article at WOS