1. Aravena, D., Atanasov, M., Neese, F.: Periodic trends in lanthanide compounds through the eyes of multireference ab initio theory. Inorg. Chem. 55, 4457–4469 (2016)
2. Basolo, F., Pearson, R.G.: Mechanisms of Inorganic Reactions: A Study of Metal Complexes in Solution, 2nd edn. Wiley, New York (1967)
3. Biltz, W., Klemm, W.: Die Unterteilung der Reichen der Übergangselemente. Ztsch. Elektrochem. 39, 597–598 (1933)
4. Biron, E.V.: Phenomena of secondary periodicity. Zh. Russ. Fiz.-Khim. Obshch. Ch. Khim. 47, 964–988 (1915). (in Russian)
5. Brauner, B.: Über die Stellung der Elemente der seltenen Erden im periodischen System. Z. Elektrochem. 14, 525–527 (1908)