Exploiting Parallel News Streams for Unsupervised Event Extraction Congle Zhang author Stephen Soderland author Daniel S Weld author 2015 text journal article Transactions of the Association for Computational Linguistics continuing MIT Press Cambridge, MA periodical academic journal zhang-etal-2015-exploiting 10.1162/tacl_a_00127 https://aclanthology.org/Q15-1009/ 2015 3 117 129