OBSERVATION OF PRETRANSITIONAL EFFECTS ON THE SHAPE OF THE E2 (17 cm-1 ) OPTICAL MODE IN β-Ag1 BY RAMAN SPECTROSCOPY E. Cazzanelli, A. Fontana, G. Mariotto, F. Rocca et M.P. Fontana J. Phys. Colloques, 42 C6 (1981) C6-776-C6-778 DOI: 10.1051/jphyscol:19816229