1. Nicholas, R.T.: Ph. D. Thesis Hull (1988).
2. Campillos, E., Marcos, M., Oriol, L.T., Serrano, J.L.: Mol. Cryst. Liq. Cryst. 215,127 (1992).
3. van Meter, J.P., Klanderman, B.H.: Mol. Cryst. Liq. Cryst. 22,285; partly: US 3.971.824 (11.6.75) (1973).
4. van Meter, J.P., Klingbiel, R.T., Genova, D.J.: Solid State Commun. 16,315 (1975).
5. van Meter, J.P., Klanderman, B.H. (Eastman Kodak): US 3.915.883 (15.8.73) (1975).