1. (Sequence from Group III to VIII in Periodic Table)
2. Gschneidner, K. A. Rare Earth Alloys, Princeton (Van Norstrand) 1961;
3. Spedding, F. H. and Daane, A. H. The Rare Earths, New York (Wiley) 1961;
4. Brauer, G. and associates in Progress in the Science and Technology of the Rare Earths I, 152, Oxford (Pergamon) 1964;
5. Bevan, D. J. M. J. inorg. nucl. Chem. 1 (1955) 49;