1. Institute of Mathematics of the Academy of Sciences of the Czech Republic Prague Czech Republic
2. Laboratoire de Mathématiques et Applications, UMR CNRS 7348 ‐ SP2MI Université de Poitiers Chasseneuil France
3. The Institute of Mathematics of the Romanian Academy Bucharest Romania
4. The Institute of Statistics and Applied Mathematics of the Romanian Academy Bucharest Romania
5. Department of Mathematical Analysis Charles University Prague Czech Republic
6. Academy for Multidisciplinary Studies Capital Normal University Beijing China