1. UFL Private University in the Principality of Liechtenstein, Triesen, Principality of Liechtenstein
2. AllDent Zahnzentrum, München, Germany
3. Department for General-, Visceral-, Thoracic-, Pediatric- and Endocrine Surgery, Johannes Wesling Hospital, University Clinic Ruhr, University Bochum, Minden, Germany
4. Vorarlberg Institute for Vascular Investigation and Treatment (VIVIT), Feldkirch, Austria.