1. E. Kittle and G. Guazzoni, Proc. of the 25th Power Sources Symposium, p.106, (1972).
2. E. Kittl, Proc. of the 10th IEEE Photovoltaic Specialists Conference, Palo Alto, California, p. 103 (1973).
3. E. Kittl, M.D. Lammert and R.J. Schwartz, Proc. of the 11th IEEE Photovoltaic Specialists Conference, Scottsdale, Arizona, p. 424 (1973).
4. M. Wolf, IEEE Trans, on Electron Devices, ED-27, p. 751 (1980).
5. M. Spitzer, J. Shewchun, E.S. Vera and J.J. Loferski, Proc. of the 14th IEEE Photovoltaic Specialists Conference, San Diego, California, p. 375 (1980).