1. Ladriere, J., Apers, D.: J. Phys. (Paris) 37, 913 (1976)
2. Wertheim, G.K.: Phys. Rev. 124, 764 (1961)
3. Ishiba, S., Yamada, M., Negita, H.: J. Phys. (Paris), Colloque C2, 40(Suppl. 3), 428 (1979)
4. Friedt, J.M., Danon, J.: At. Energy Rev. 184, 893 (1980)
5. Perfiliev, Y.D.: Izv. Ross. Akad. Nauk. Ser. Fiz. (Bulletin of the Russian Academy of Science. Ser. Phys., in Russian) 63, 1383 (1999)