1. L. Richter Dissertation Halle (Saale) 1979
2. A.Biering, D.Demus, L.Richter, H.Sackmann, A.Wiegeleben and H.Zaschke Mol.Cryst.Liqu.Cryst. in print
3. L.Richter, D.Demus and H.Sackmann Mol.Cryst.Liqu.Cryst. in preparation
4. H. Sackmann J.de Phys.Colloq. C 3 40 C3-5 (1979)
5. H.Sackmann Reports III. Liquid Crystal Conference Budapest (1979) in print