1. Faculty of Medicine, Aleppo University, Aleppo
2. Department of Cardiothoracic Surgery, Damascus University Cardiovascular Surgical Center, Damascus
3. Department of Pediatric Surgery, Children’s Hospital
4. Peoples’ Friendship University of Russia: Rossijskij universitet druzby narodov, Moscow, Russia
5. Department of Otolaryngology, Al-Bassel Hospital, Tartus, Syrian Arab Rebublic