1. Department of First General Surgery, Cangzhou Central Hospital, Hebei, P.R. China
2. Department of Surgery, Cangzhou Haixing County Hospital, Hebei, P.R. China
3. Department of Surgery, Cangzhou Suning Renhe Hospital, Hebei, P.R. China
4. Department of Pharmacy, Cangzhou Maternity and Child Care Hospital, Hebei, P.R. China