SYMMETRY OF SPIN WAVES AND HALDANE GAP IN CsNiCl3 Z. Tun, W. J. L. Buyers, R. L. Armstrong, E. D. Hallman et D. P. Arovas J. Phys. Colloques, 49 C8 (1988) C8-1431-C8-1432 DOI: 10.1051/jphyscol:19888656