1. Institute of Geotechnics, Slovak Academy of Sciences, Watsonova 45, 04001 Košice, Slovakia
2. Jozef Stefan Institute, Jamova cesta 3, S1-1000 Ljubljana, Slovenia
3. Institute of Physics of the Czech Academy of Sciences, Cukrovarnická 10/112, 16200 Prague, Czech Republic
4. Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 04001 Košice, Slovakia