1. A. Sommerfeld andH. Bethe, “Elektronentheorie der Metalle”, in Handbuch der Physik edited by A. Smekal (Springer, Berlin, 1933), Vol. 24/2, Sec. 3.
2. The foundations and applications of the model are given in the article byP. Gombás, “Statistische Behandlung des Atoms”, in Handbuch der Physik, edited by S. Flügge (Springer, Berlin, 1956), Vol. 36, Sec. 2.
3. P. Gombás, Acta Phys. Hung.,3, 105, 1953;3, 127, 1953.
4. P. Gombás, Acta Phys. Hung.,5, 483, 1956.
5. R. M. Bozorth, “Ferromagnetism”, p. 462 (Nostrand, Princeton, 1951).