1. R.E. Moss: Advanced Molecular Quantum Mechanics. ( Chapman and Hall, 1973 ).
2. See e.g. M. Born and K. Huang: Dynamical Theory of Crystal Lattices. (Oxford University Press, 1954 ).
3. N.F. Ramsey: Molecular Beams. (Oxford Univ. Press, 1956 ).
4. D.W. Davies: The Theory of the Electric and Magnetic Properties of Molecules. (J. Wiley, 1967 ).
5. F. London, J.Phys.Radium (Paris) 8, 397 (1937).