1. Official Journal of the European Union (L37) (2003), 19; 24. ( http://europa.eu.int/eur-lex/lex/JOHtml.do?uri=OJ:L:2003:037:SOM:EN:HTML )
2. See any text book on Inorganic Chemistry, e.g., N. Wiberg, Hollemann-Wiberg: Lehrbuch der Anorganischen Chemie, 102nd ed. (Berlin - New York: de Gruyter, 2007).
3. P. Villard and L.D. Calvert, Pearson’s Handbook of Crystallographic Data for Intermetallic Phases, 2nd ed., Vol. 4 (Materials Park, OH: ASM International, 1991), p. 5285.
4. W.J. Plumbridge, J. Mater. Sci. Mater. Electron. 18, 307 (2007).
5. G. Tamman and K.L. Dreyer, Z. Anorg. Chem. 199, 97 (1931).