1. PV New, PV Energy Systems, Inc., Virginia, Feb. (1991).
2. and , Proceedings of International PVSEC-4, Sydney, 1989, p. 435.
3. and , Proceedings of 9th EC Photovoltaic Solar Energy Conference, 1989, p. 362.
4. , and , Technical Digests of International PVSEC-5, Kyoto, 1990, p. 323.
5. , , and , Proceedings of 10th EC Photovoltaic Solar Energy Conference, Lisbon, 1991, p. 254.