Z. Zhang, X. Han, Z. Liu, X. Jiang, M. Sun, and Q. Liu. Proceedings of the 57th Annual Meeting of the Association for Computational Linguistics, page 1441--1451. Florence, Italy, Association for Computational Linguistics, (July 2019)
Y. Liang, S. Ke, J. Zhang, X. Yi, and Y. Zheng. Proceedings of the Twenty-Seventh International Joint Conference on Artificial Intelligence, International Joint Conferences on Artificial Intelligence Organization, (July 2018)