1. Aasa, R., 1970, J. Chem. Phys., 52:3919.
2. Abragam, A., and Bleaney, B., 1970, Electron Paramagnetic Resonance of Transition Ions, Clarendon, Oxford.
3. Alexander, S, Luz, Z., Naor, Y., and Poupko, R., 1977, Mol. Phys. 33:1119.
4. Allen, B. T., 1965, J. Chem. Phys. 43:3820.
5. Anderson, P. W., 1963, Magnetism, Vol. I (G. T. Rado, and H. Suhl, eds.), Academic, New York.