1. Ladd MFC, Povey DC (1972) J Cryst Mol Struct 2:243
2. International critical tables 3:80 (1928), 7:73 (1930); Mellor’s treatise on inorganic and theoretical chemistry 2:941 (supplement, 1961)
3. Bull RJ et al (1973) Cryst Struct Commun 2:625
4. Ladd MFC, Povey DC (1976) Acta Crystallogr B32:1311
5. Kusters W, de Mayo P (1974) J Am Chem Soc 96:3502