1. Proceedings of the 12th EU Photovoltaic Solar Energy Conference, Amsterdam, 1994; 971-974.
2. Proceedings of the 13th EU Photovoltaic Solar Energy Conference, Nice, 1995; 390-394.
3. Proceedings of the 14th EU Photovoltaic Solar Energy Conference, Barcelona, 1997; 157-160.
4. Proceedings of the 2nd World Conference on Photovoltaic Solar Energy Conversion, Vienna, 1998; 1193-1198.