1. L. Eberson and B. Helgee,Chemica Scripta 5 (1974) 47.
2. Idem, Acta Chem. Scand. B29 (1975) 4.
3. Idem, ibid. B31 (1977) 813.
4. Idem, ibid. B32 (1978) 3.
5. R. Dworak and H. Wendt, ?Proceedings of the 27th Meeting of International Society of Chemistry?, Zurich (1976).