1. D.L. Williamson, L. Niesen, G. Weyer, R. Sielemann and G. Langouche, in:Hyperfine Interactions of Defects in Semiconductors, ed. G. Langouche (Elsevier, Amsterdam, 1992) pp. 1ff.
2. Th. Wichert, N. Achtziger, H. Metzner and R. Sielemann, in:Hyperfine Interactions of Defects in Semiconductors, ed. G. Langouche (Elsevier, Amsterdam, 1992) pp. 79ff.
3. F.H. Eisen, Phys. Rev. 135 A (1964) 1394.
4. G. Weyer, H. Grann and F.T. Pedersen, Mater. Sci. Forum 10–12 (1986) 1189.
5. G. Weyer, H. Andreasen and H. de Waard, Phys. Stat. Sol. (b) 132 (1985) 219.