1. Department of Chemistry University of Veterinary Medicine H-1400 Budapest, P.O.Box 2 Hungary
2. Department of Chemistry University of Technology and Economics H-1111 Budapest, Szt. Gellért tér 4 Hungary
3. Department of Physical Chemistry University of Debrecen 4032 Debrecen Hungary
4. Department of Organic Chemistry University of Debrecen, P. O. Box 400 4002 Debrecen Hungary