1. S.G. Brush: The history of the Lenz-Ising 883 (1967)
2. W. Lenz: Phys. Z. 21, 613 (1920)
3. E. Ising: Z. Physik 31, 253 (1925)
4. H. Bethe: Proc. Roy. Soc. (London) 9, 244 (1938). Also: F. Cernuschi
5. R. Fowler, E. Guggenheim: Statistical Thermodynamics (Cambridge Univ. Press, Cambridge 1939) Chap.13