1. Puska MJ, Lanki P, Nieminen RM (1989) J Phys: Condens Matter 1:6081
2. Bischof G, Gröger V, Krexner G, Nieminen RM (1996) J Phys: Condens Matter 8:7523
3. Nieminen RM, Manninen MJ (1979) In: Hautojärvi P (ed) Positrons in solids, springer series topics in current physics. Springer-Verlag, Berlin, pp 143
4. Schulz PJ, Lynn KG (1988) Rev Modern Phys 60:701
5. Puska MJ, Nieminen RM (1994) Rev Modern Phys 66:841