1. Fujian Police College, Fuzhou, Fujian 350000, China
2. The Key Laboratory of Document Examination of the Ministry of Public Security, Shenyang, Liaoning 110000, China
3. Shenzhou Judicial Appraisal Center, Nanchang, Jiangxi 330000, China
4. Department of Documents Examination, Criminal Investigation Police University of China, Shenyang, Liaoning 110000, China