1. S. Methfessel and D. C. Mattis in Handbuch der Physik XVIII/I (Springer-Verlag 1968), pp. 389–553.
2. G. Busch and P. Wachter, Phys. Kondens. Materie 5, 232(1966).
3. G. Busch and P. Wachter, Z. Angew. Physik 26, 1(1968).
4. G. Busch, J. Appl. Phys. 38, 1386(1967).
5. P. Wachter, Helv. Phys. Acta 41, 1249(1968).