References and Notes for Neptunium ( Np )

BW92b J. Blaise and J.-F. Wyart, Energy Levels and Atomic Spectra of Actinides, International Tables of Selected Constants 20, Paris (1992). Also available at http//www.lac.u.psud.fr/Database/Contents.html. The authors note that the Np II energy-level analysis is preliminary. Only one Np II line is given with an energy-level classification.
FTBC76 M. Fred, F. S. Tomkins, J. E. Blaise, P. Camus, and J. Vergés, Argonne Natl. Lab. Rep. No. 76-68 (1976).
KDEE97 S. Köhler, R. Diessenberger, K. Eberhardt, N. Erdmann, G. Herrmann, G. Huber, J. V. Kratz, M. Nunnemann, G. Passler, P. M. Rao, J. Riegel, N. Trautmann, and K. Wendt, Spectrochim. Acta B 52, 717 (1997).