[2] Ε. P. Gupta, J. Freyer; Int. J. Electronics, 1979, 47, No. 5, 459.
[3] Tatsuyuki Sanada, Osamu Wada; Japan. J. Appl. Phys., 1980, 19, No. 9, 491.
[4] G. H. Olsen et al., Appl. Phys. Lett., 1979, 34, No. 4, 262.
[5] G. Weimann; Phys. Status. Solicli A (germany), 1978, 50, No. 2, 219.
