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2. J. K. Percus,J. Stat. Phys. 15:505 (1976).
3. J. K. Percus,J. Chem. Phys. 75:1316 (1981).
4. J. K. Percus, inStudies in Statistical Mechanics, E. W. Montroll and J. L. Lebowitz, eds. (North-Holland, Amsterdam, 1982).
5. See, e.g., E. L. Ince,Ordinary Differential Equations, (Longmans, Green, London, 1926).