1. Boehm, H. P., Diehl, E., Heck, W., Sappok, R.: Angew. Chem. 76, 742 (1964); Angew. Chem. Intern. Ed. 3, 669 (1964)
2. Johnson, B. F. G. (ed.): Transition Metal Clusters, Chichester, New York, Brisbane, Toronto, J. Wiley & Sons 1980
3. Boehm, H. P.: Adv. Catal. 16, 179 (1966)
4. Eischens, R. P., Pliskin, W. A.: Adv. Catal. 10, 1 (1958)
5. Crawford, V.: Quart. Rev. 14, 378 (1960)