Martin, W.
, Zalubas, R.
and Hagan, L.
(1978),
Atomic energy levels - the rare-earth elements ::the spectra of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetitum, , National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NBS.NSRDS.60
(Accessed October 9, 2024)