1. Sioda, R.E., Koski, W.S.: J. Am. Chem. Soc. 89 (1967) 475.
2. Voss, J., Walter, W.: Justus Liebigs Ann. Chem. 743 (1971) 177.
3. Voss, J., Walter, W.: Tetrahedron Letters 1968, 1751.
4. Voss, J., Schlapkohl, K.: Tetrahedron 31 (1975) 2982.
5. Stradins, J., Baider, L.M., Baumane, L., Gavars, R., Glezer, V.: Elektrokhimiya 13 (1977) 759.