1. A. Mueller, S. H. Fox and R. I. Day,Anal. Chem. 22 (1950) 1570.
2. M. S. Brooks and J. K. Kennedy (ed.), ?Ultrapurification of Semiconductor Materials?, The Macmillan Company, New York (1962) p. 182.
3. V. A. Mikhailov, L. I. Shchukin, S. I. Sokolova and I. G. Yudelevich,Zentralinst Festkoerperphys Werkstofforsch 22 (1981) 1;Chem. Abstr. 97 (1982) 96050t.
4. L. A. Nisel'son, Z. N. Orshanskaya, K. V. Tret'yakeva, A. D. Miklyaev, V. P. Borisova and V. N. Kazimirov,Izv. Akad. Nauk SSSR Met. 4 (1982) 51;Chem. Abstr. 97 (1982) 201185r.
5. F. Deml and V. Gaislova,Coll. Czech. Chem. Commun. 25 (1960) 2213.