Luo, Bingjun, Junjie Zhu, Tianyu Yang, Sicheng Zhao, Chao Hu, Xibin Zhao, and Yue Gao. “Learning Deep Hierarchical Features With Spatial Regularization for One-Class Facial Expression Recognition”. Proceedings of the AAAI Conference on Artificial Intelligence 37, no. 5 (June 26, 2023): 6065–6073. Accessed May 13, 2026. https://ojs.aaai.org/index.php/AAAI/article/view/25749.