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2. Maier, W. and Saupe, A. (1958) Z. Naturf. (a), 13, pp. 564 - 564. Ibid., 14, 882; 1960, Ibid., 15, 287.
3. Luckhurst, G.(1979) The Molecular Physics of Liquid Crystals. Academic Press. Chap. 4
4. Ypma, J.G.J. and Vertogen, G. (1976) J. Phys. Paris, 37, pp. 557 - 557. C-1,
5. Ypma, J.G.J. and Vertogen, G. and Koster, H.T. (1976) Molec. Crystals liq. Crystals, 37, pp. 57 - 57.