1. For reviews see: Hydrogen in metals I. Alefeld, G., Völkl, J. (eds.). Berlin, Heidelberg, New York: Springer 1978
2. For reviews see: Physics of superionic conductors. M.B. Salamon (ed.). Berlin, Heidelberg, New York: Springer 1979
3. Dieterich, W., Fulde, P., Peschel, I.: Adv. Phys.29, 527 (1980)
4. Zwerger, W.: Z. Phys. B-Condensed Matter42, 333 (1981)
5. See: Physics of intercalation compounds. Pietronero, L., Tosatti, E. (eds.). Berlin, Heidelberg, New York: Springer 1981