1. C. S. Smith:Met Trans., 1975, vol.6, p. 603.
2. M. Tenenbum:Met. Trans., 1976, vol.T, p. 339.
3. W. O. Bker:Met. Trans., 1976, vol. 8/1, p. 339.
4. For an excellent historic l description of the evolution of the Periodic Table see: J. W.vanSpronsen:The Periodic System of Chemic l Elements: History of the First Hundred Years, Elsevier Publishing Co., Amsterdam, London, New York, 1969.
5. DBSnaturliche System der chemischen Elemente, bhandlungen von Loth r Meyer and D. Mendelejeff, K. Seubert, ed., Ostw ld’s Kl ssiker No. 68, Leipzig, 1895.