THE HYPERFINE SPLITTING OF HOLMIUM NEAR AN ENERGY CROSSOVER IN YTTRIUM ETHYLSULPHATE C. Carboni, R. L. Cone, Z.-P. Han et M. A. H. McCausland J. Phys. Colloques, 49 C8 (1988) C8-843-C8-844 DOI: 10.1051/jphyscol:19888380