1. Ph. D. Thesis No. 9301 ETH, Zurich, Switzerland, 1990.
2. Ph. D. Thesis No. 11253 ETH, Zurich, Switzerland, 1995.
3. Ph. D. Thesis, TU Erlangen-Nuremberg, Erlangen, Germany, 1987.
4. Ph. D. Thesis, TU Erlangen-Nuremberg, Erlangen, Germany, 1990.
5. Ph. D. Thesis, TU Erlangen-Nuremberg, Erlangen, Germany, 1992.