1. Institute of Low Temperature and Structure Research
2. Polish Academy of Sciences
3. 50-950 Wrocław 2
4. Poland
5. Faculty of Fundamental Problems of Technology
6. Wrocław University of Technology
7. Wrocław
8. CNR-SPIN
9. 67100 L'Aquila
10. Italy
11. Department of Physical and Chemical Sciences
12. University of L'Aquila
13. Departamento de Fisica de la Materia Condensada
14. Facultad de Ciencia y Tecnologia
15. UPV/EHU
16. Bilbao
17. Spain