1. H. Keller: Mol. Cryst. Liq. Cryst. 21, 1 (1979)
2. F. Reinitzer: Monatsh. 9, 421 (1888)
3. G. W. Gray: in: “Polymer Liquid Crystals”, eds. A. Ciferri, W. R. Krigbaum and R. B. Meyer: Academic Press, NY (1982) chap. 1 and literature cited herein
4. G. W. Gray: in: “The Molecular Physics of Liquid Crystals”, eds. G. R. Luckhurst, G. W. Gray: Academic Press, NY (1979) chap. 1
5. G. W. Gray, P. A. Winsor: in: “Liquid Crystals and Plastic Crystals” eds. G. W. Gray, P. A. Winsor: Vol. 1, Ellis Horwood, Chichester England (1974)