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3. See, for instance, R. Rein, P. Claverie, and J. Pollak, Int. J. Quantum Chem. 2, 129 (1968).
4. E. F. Haugh and J. O. Hirschfelder, J. Chem. Phys. 23, 1778 (1955).
5. K. Laki and J. Ladik, Int. J. Quantum Chem., Quantum Biol. Symp. 3, 51 (1976).