1. Lutz, H.D., Haeuseler, H.: J. Solid State Chem. 13 (1975) 215.
2. Huster, J.: Z. Anorg. Allg. Chem. 447 (1978) 89.
3. Huster, J.: Z. Kristallogr. 149 (1979) 146.
4. van Laar, B., Engelsman, F.M.R.: J. Solid State Chem. 6 (1973) 384.
5. van Bruggen, C.F., Wiegers, G.A., Haange, R.J., Tolsma, P.: VIth Int. Conf. Solid Compounds of Transition Elements, Stuttgart 1979; Collected Abstr. p. 242.