1. Faculty of Humanities and Natural Sciences, University of Prešov, 17. novembra 1, 081 16 Prešov, Slovakia
2. Department of Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova, Italy
3. CNR-SPIN, Corso Ferdinando Maria Perrone 24, 16152, Genova, Italy
4. Highly Correlated Matter Research Group, Department of Physics, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa
5. Institute of Experimental Physics, SAS, Watsonova 47, 040 01 Košice, Slovakia