1. Institute of Mathematics, ELTE Eötvös Loránd University, Budapest, Hungary;
2. Institute of Chemistry, ELTE Eötvös Loránd University, Budapest, Hungary;
3. Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Budapest, Hungary;
4. Faculty of Economics, Socio-Human Sciences and Engineering, Sapientia – Hungarian University of Transylvania, Miercurea-Ciuc, Romania