1. Y. Hamakawa and Y. Tawada: Intern. J. Solar Energy 1 (1982) 251.
2. Y. Tawada, M. Kondo, H. Okamoto and Y. Hamakawa: Solar Energy Mat. 6 (1982) 299.
3. S.R. Ovshinsky: Materials Research Soc. 1985 Spring Meeting, San Francisco (1985) 251.
4. S. Tsuda, H. Tarui, T. Matsuyama, H. Haku, K. Watanabe, Y. Nakashima, S. Nakano and Y. Kuwano: Proc. 2nd Intern. Photovoltaic Science and Engineering Conf., Beijing, China (1986) 409.
5. For example, JARECT vol. 6, ed. by Y. Hamakawa ( Ohm-Sha & North-Holland, Tokyo, 1983 ) p. 252.