Unsupervised Tree Induction for Tree-based Translation Feifei Zhai author Jiajun Zhang author Yu Zhou author Chengqing Zong author 2013 text journal article Transactions of the Association for Computational Linguistics continuing MIT Press Cambridge, MA periodical academic journal zhai-etal-2013-unsupervised 10.1162/tacl_a_00224 https://aclanthology.org/Q13-1020/ 2013 1 243 254