RESONANT RAMAN SCATTERING OF 23 cm-1 PHONONS BY Dy3+ IONS IN LaF3 S.S. Yom, R.S. Meltzer and J.E. Rives J. Phys. Colloques, 46 C7 (1985) C7-247-C7-251 DOI: 10.1051/jphyscol:1985745