1. Institute of Physics, University of Silesia, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
2. Institute of Applied Geology, Silesian Technical University, Akademicka 2A, 44-100 Gliwice, Poland
3. Institute of Physics, Silesian University of Technology, Konarskiego 22B, 44-100 Gliwice, Poland