1. Center for Mathematical Analysis, Geometry and Dynamical Systems , Mathematics Department , Instituto Superior Técnico , Universidade de Lisboa , Av. Rovisco Pais, 1049-001 Lisboa , Portugal
2. Department of Applied Mathematics , University of Agriculture , ul. Balicka 253c, 30-19 8 Kraków , Poland
3. Institute of Mathematics , Maria Curie-Skłodowska University , pl. M. Curie-Skłodowskiej 1, 20-031 Lublin , Poland
4. Department of Applied Mathematics , University of Agriculture , ul. Balicka 253c, 30-198 Kraków , Poland