hafnium

[1982] Some Details in the Prehistory of the Discovery of Element 72 ; V. P. Mel'nikov ; Centaurus 26 (1982) p. 317 [lien]
[1994] Prediction of the nature of hafnium from chemistry, Bohr's theory and quantum theory ; Eric R. Scerri ; Annals of Science 51 (1994) p. 137 [lien]