1. Faculty of Physics and Applied Informatics, University of Łódź, Pomorska 149/153, PL-90-236 Łódź, Poland
2. Institute of Mathematics, Polish Academy of Sciences, Śniadeckich 8, P.O.B. 21, PL-00-956 Warszawa, Poland
3. Department of Computer and System Analysis, College of Humanities and Sciences, Nihon University, Sakurajosui 3-25-40, 156-8550 Setagaya, Japan
4. Department of Analysis and Differential Equations, University of Warmia and Mazury, Słoneczna 54, PL-10-710 Olsztyn, Poland
5. Institute of Mathematics and Informatics, State School of Higher Education in Chełm, Pocztowa 54, PL-22-100 Chełm, Poland