1. Department of Gastrointestinal Surgery The Affiliated Hospital of Qingdao University Qingdao Shandong China
2. Department of Colorectal Surgery Weifang People's Hospital Weifang Shandong China
3. Department of Gastrointestinal Surgery The People's Hospital of Jimo Qingdao Qingdao Shandong China
4. Department of Gastrointestinal Surgery The People's Hospital of Dongying Shandong Dongying Shandong China
5. Department of Gastrointestinal Surgery Juxian People's Hospital Rizhao Shandong China
6. General Surgery Department Qingdao Hospital University of Health and Rehabilitation Sciences (Qingdao Municipal Hospital) Qingdao Shandong China
7. General Surgery Department 971st Naval Hospital Qingdao Shandong China
8. General Surgery Department Jining No 1 People's Hospital Jining Shandong China
9. Department of Gastrointestinal Surgery Weifang Yidu Central Hospital Weifang Shandong China