1. Jordan, R.G.: Contemp. Phys.15, 375 (1974)
2. Liu, S.H.: Handbook on the Physics and Chemistry of Rare Earths. Vol. 1: Metals. Gschneidner, K.A. Jr., Eyring, L.R. (eds.), p. 233. Amsterdam: North Holland 1978
3. Eastman, D.E.: Solid State Commun.7, 1697 (1969)
4. Young, R.C.: J. Phys. Colloq. (Paris)40, C5?71 (1979)
5. Mackintosh, A.R., Andersen, O.K.: Electrons at the Fermi surface. Springford, M. (ed.). Cambridge: Cambridge University Press 1980