1. B. G. Baldwin,J. Iron and Steel Inst. 177 (1954) 312.
2. M. Jon andM. Rouby,Chimie Anal. 49 (1967) 73.
3. A. Goetz andP. Ilie,Rev. Mineral. 20 (1969) 216.
4. S. Isakova andT. Vasilev,Rudodobiv. Met. 22 (1967) 558.
5. I. Uchiyama andT. Saito, Proc. Mem. Lect. Meet. Anniv. Found. Nat. Res. Inst. Metals 10th, Tokyo (1966) p. 122.