1. J. Nihoul, inInterstitials and Vacancies in Metals eds., A. Seeger, D. Schumacher, W. Schilling and J. Diehl (North Holland, Amsterdam, 1970).
2. H. Wever and W. Seith, inDefects and Defect Clusters in Bcc Metals and their Alloys, ed. R. J. Arsenault (Nat. Bur. Standards, Garthersburg, MD, 1973).
3. S. R. Reintsema, S. A. Drentje, and J. de Waard, Hyp. Int.5, 167 (1978).
4. P. Hautoj�rvi, T. Judin, A. Vehanen, J. Yli-Kauppila, J. Johansoon, J. Verdone, and P. Moser, Solid State Comm.29, 855 (1979).
5. Fundamental Aspects of Radiation Damage in Metals, eds. M. T. Robinson and F. W. Young (Nat. Technical Information Service, Springfield, VA, 1975).