1. R.D. Fischer in “NMR of Paramagnetic Molecules”, G.N. LaMar, W. DeW. Horrocks and R.H. Holm, Eds., Academic Press, New York and London, 1973, Chap. 13 (p. 522).
2. R.D. Fischer in “Organometallics of the f-Elements”, T.J. Marks and R.D. Fischer, Eds., D. Reidel Publ. Comp., Dordrecht/Boston, 1979, p. 337.
3. ACS Symp. Ser. 131;WD Luke,1980
4. W. Jahn, K. Yünlü, W. Oroschin, H.-D. Amberger and R.D. Fischer, Inorg. Chim. Acta 95 (1984) 85
5. A. Streitwieser, Jr., Inorg. Chim. Acta 94 (1984) 171.