1. F.A. Cotton,Inorg. Chem., 1964,3, 1217–1220
2. For general reviews of metal cluster chemistry see for example: E.L. Muetterties,Chem. Eng. News, Aug. 30th, 1982, pp. 28–41; F.A. Cotton and M.H. Chisholm,Chem. Eng. News, Jun. 28th, 1982, pp. 40–54; B.F.G.Johnson, ‘Transition Metal Clusters’, John Wiley and Sons, New York, 1980
3. J.D. Corbett,Accounts Chem. Res., 1981,14, 239–246
4. H.-D. Sinnen and H.-U. Schuster,Z. Naturforsch., 1981,36b, 833
5. P. Chini,J. Organometal. Chem., 1980,200, 37–61