1. Faculty of Applied Mathematics AGH University of Science and Technology Kraków Poland
2. Department of Mathematics University of Craiova Craiova Romania
3. Brno University of Technology Faculty of Electrical Engineering and Communication Brno Czech Republic
4. Universidade Federal do Pará Faculdade de Matemática Belém Pará Brazil
5. Universidade Federal do Cariri Centro de Ciências e Tecnologia Juazeiro do Norte Ceará Brazil