Luo, Minnan, Feiping Nie, Xiaojun Chang, Yi Yang, Alexander Hauptmann, and Qinghua Zheng. 2017. “Probabilistic Non-Negative Matrix Factorization and Its Robust Extensions for Topic Modeling”. Proceedings of the AAAI Conference on Artificial Intelligence 31 (1). https://doi.org/10.1609/aaai.v31i1.10832.