TY - RPRT TI - Atomic energy levels as derived from the analyses of optical spectra : volume II. 24Cr to 41Nb AU - Moore, Charlotte E PY - 1971 PB - National Bureau of Standards CY - Gaithersburg, MD SN - NBS NSRDS 35v2 DO - 10.6028/NBS.NSRDS.35v2 ER -