1. International Chair of Mathematical Physics and Applications (ICMPA-UNESCO Chair), University of Abomey-Calavi, Cotonou, Benin
2. Centre International de Recherches et d'Etude Avancees en Sciences Mathematiques & Informatiques et Applications (CIREASMIA), Cotonou, Benin
3. Center of Applied Mathematics, Faculty of Mechanical Engineering (CAM-FMEN),
University of Nis, Nis, Serbia