WAVELENGTHS AND ENERGY LEVELS FOR n = 3 - 3 TRANSITIONS IN F-LIKE IONS : Cr XVI, Fe XVIII, Ni XX AND Cu XXI J.P. BUCHET et M.C. BUCHET-POULIZAC J. Phys. Colloques, 49 C1 (1988) C1-255-C1-258 DOI: 10.1051/jphyscol:1988154