Citation: Evgeny Todorov; Slavi C. Sevov (1997). Synthesis, Characterization, and Bonding of Heteroatomic Clusters: Na13Cd20E7 (E = Pb, Sn), a Further Example of a Structure Containing Empty Icosahedra without an Element of Group 13. Inorganic Chemistry, 36, pp. 4298-4302.