1. Zuchun, W.: Discussion on tongue image acquisition method and Application in tongue diagnosis Objectification research [D]. Guangzhou University of Chinese Medicine (2011). (in Chinese)
2. Shenhua, J., Jiang, L.: Research progress on objectification of tongue image and nature of tongue coating. Shanghai J. Tradit. Chinese Med. 50(07), 94–97 (2016). (in Chinese)
3. Cai, Y.-H., Hu, S.-B., Guan, J., et al.: Development analysis and application of Objectified tongue diagnosis technology in Chinese medicine. World Sci. Technol. Modernization Chinese Med. 23(07), 2447–2453 (2021). (in Chinese)
4. Pang, W., Zhang, D., Zhang, J.: Tongue features of patients with coronavirus disease, a retrospective cross-sectional study. Integr. Med. Res. 9(3), 100493 (2019)
5. Xingzheng, W., Bob, Z., Zhimin, Y., et al.: Statistical analysis of tongue images for feature extraction and diagnostics. IEEE Trans. Image Process. 22(12), 5336–5347 (2013)