1. Donaldson, J.D., Moser, W., Simpson, W.B.: J. Chem. Soc. 1964, 323–326.
2. Gilli, G., Pulidoni, F.: Ann. Chim. (Rome) 56 (1966) 1320–1331.
3. Brun, G., Barnoyer, B.: Compt. Rend. 269C (1969) 1213–1215.
4. Ebert, M., ∼ediv∼’, J.: Czech. 3. Phys. B 17 (1967) 698–702.
5. Colton, R.H., Henn, D.E.: J. Chem. Soc. A 1971, 1207–1209.