1. National Institute of Materials Physics, Atomiştilor 405A, 077125 Măgurele, Romania
2. Laboratoire de Physico-Chimie des Matériaux, Université de Monastir, Avenue de l'Environnement, 5019 Monastir, Tunisia
3. Faculty of Electronics, Telecommunications and Information Technology, Politehnica University, Iuliu Maniu 1-3, 061071 Bucharest, Romania
4. Faculty of Physics, University of Bucharest, Atomiştilor 405, 077125 Măgurele, Romania