1. An account of the early history of magnetic research is given in Ch. I of D. C. Mattis, ?The Theory of Magnetism,? Harper & Row, (1965).
2. Recent work in nanomagnetism is described in a collection of articles in ?Physics Today,? April (1995).
3. I. Affleck,J. Phys. CM 1, 3047 (1989).
4. J. L. van Hemmen, S. Suto,Europhys. Lett. 1, 481 (1986),and Physica B 141, 37 (1986).
5. M. Enz and R. Schilling,J. Phys. C 19, 1765 (1986);ibid L 711 (1986).