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2. G. A. Baker, Jr., H. E. Gilbert, J. Eve, and G. S. Rushbrooke, A Data Compendium of Linear Graph, BNL 50053 T-46B (Brookhaven National Laboratory 1967) and references therein.
3. See also T. Morita, J. Math. Phys. 13, 115 (1972).
4. M. Kurata, R. Kikuchi and T. Watari, J. Chem. Phys. 21, 435 (1953).
5. S. Katsura and M. Takizawa, Prog. Theor. Phys. 51, 82 (1974).