Laing, Michael (2005). "A Revised Periodic Table: With the Lanthanides Repositioned". Foundations of Chemistry. 7 (3): 203–233. doi:10.1007/s10698-004-5959-9. S2CID97792365.
Laing, Michael (2005). "A Revised Periodic Table: With the Lanthanides Repositioned". Foundations of Chemistry. 7 (3): 203–233. doi:10.1007/s10698-004-5959-9. S2CID97792365.
stuartcantrill.com
Cantrill, Stuart (21 November 2018). "Promethium unbound". Chemical connections. Retrieved 30 December 2019.