1. I. Noddack, W. Noddack,Z. Physik. Chem., 154 (1931) 207.
2. V.M. Goldschmidt, Cl. Peters,Nachr. Akad. Wiss. Göttingen, Math-Phys., K1. IV (1932) 377.
3. R. Robert, E. Van Wyk, Johannesburg, Nat. Inst. for Metallurgy, Laboratory Method No 78/5, 1970.
4. R. Robert, E. Van Wyk, R. Palmer, Johannesburg, Nat. Inst. for Metallurgy, Report no 1371, 1971.
5. M. Hansen (Ed.), Constitution of Binary Alloys, McGraw-Hill, New York-Toronto-London, 1958, p. 1034.