Luo, Minnan, Feiping Nie, Xiaojun Chang, Yi Yang, Alexander Hauptmann, and Qinghua Zheng. “Probabilistic Non-Negative Matrix Factorization and Its Robust Extensions for Topic Modeling”. Proceedings of the AAAI Conference on Artificial Intelligence 31, no. 1 (February 13, 2017). Accessed May 3, 2024. https://ojs.aaai.org/index.php/AAAI/article/view/10832.