1. Laboratoire d'équations aux dérivées partielles non linéaires et histoire des mathématiques Ecole Normale Supérieure Algiers Algeria
2. Institute of Problems of Mechanical Engineering Russian Academy of Sciences Saint Petersburg Russia
3. Institute of Fundamental Technological Research Polish Academy of Sciences Warsaw Poland
4. Institut Camille Jordan, UMR 5208 CNRS University Lyon 1 Villeurbanne France
5. Peoples' Friendship University of Russia 6 Miklukho‐Maklaya St Moscow Russia