1. D. Seidman, Surface Sci.,70, 532 (1978).
2. V. A. Kuznetsov, G. M. Kukavadze, and A. L. Suvorov, Prib. Tekh. Eksp., No. 2, 152 (1969).
3. M. Robinson, in: Radiation Damage in Metals, Am. Soc. Met., Metals Park, Ohio (1976), p. 1.
4. D. G. Brandon, J. Sci. Instrum.,41, 373 (1964).
5. A. L. Suvorov, in: Structure and Properties of Single Crystals of Refractory Metals [in Russian], Nauka, Moscow (1973), p. 52.