1. Bertini, I., Luchinat, C.: In: Metal Ions in Biological System, (ed. H. Sigel) vol. 15, in press
2. Chelebowski, J. F., Coleman, J. E.: ibid. vol. 6, 2 (1976)
3. Lindskog, S.: Structure and Bonding 8, 153 (1970)
4. Vallee, B. L.: Trends. Biochem. Sci. 1, 88 (1976)
5. Bertini, I., Luchinat, C., Scozzafava, A.: Structure and Bonding 48, 45 (1982)