1. Helios Klinikum Jerichower Land; Teaching Hospital of the Otto-von-Guericke University; Burg Germany
2. Cirurgia do Aparelho Digestivo, Gastroenterologia; São Bento do Sul Santa Catarina Brazil
3. Therapeutic Endoscopy, Basil I. Hirschowitz Endoscopic Center of Excellence; University of Alabama; Birmingham Alabama USA
4. University of Belgrade; Belgrade Serbia