Phonon anomalies in displacive phase transitions by surface X-ray scattering G. Landmesser, T.R. Finlayson, R.L. Johnson, M. Aspelmeyer, A. Plech, J. Peisl et U. Klemradt J. Phys. IV France, 112 (2003) 123-127 DOI: 10.1051/jp4:2003848