Institution: | 1. Department of Mathematics, West University of Timişoara, Bd. V. Parvan nr. 4, 300223 Timişoara, Romania;2. Department of Physics, West University of Timişoara, Bd. V. Parvan nr. 4, 300223 Timişoara, Romania;3. L.A.G.A, UMR 7539, Institut Galilée, Université Paris 13, 99 Avenue J.B. Clément, 93430 Villetaneuse, France |