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2. Dissociation Energies and Spectra of Diatomic Molecules 3rd edn. (Chapman and Hall, London, 1968), pp. 60-68.
3. The Crossing of Potential Surfaces.
4. and Quantum Chemistry (Wiley, New York, 1963), p. 206.
5. and ?Chemical binding?, in Quantum Theory, Vol. 2, Ed. (Academic Press, New York, 1962), p. 204.