1. Jinzhou Medical University, Jinzhou, Liaoning, China.
2. Department of Thyroid and Breast Surgery, the 960th Hospital of People's Liberation Army, Jinan, China.
3. Department of General Surgery, the 963rd Hospital of People's Liberation Army, Jiamusi, China.
4. Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China.