1. Proc. 23rd IEEE Photovoltaic Specialists Conf.;Hedestrom,1993
2. Proc. 23rd IEEE Photovoltaic Specialists Conf.;Saito,1993
3. Proc. 11th EC Photovoltaic Energy Conf.;Kessler,1992
4. 21st IEEE Photovoltaic Specialists Conf.;Yamanaka,1990
5. 11th EC Photovoltaic Energy Conf.;Bodegard,1992