Cross-document Temporal and Spatial Person Tracking System Demonstration Heng Ji author Zheng Chen author 2009-06 text Proceedings of Human Language Technologies: The 2009 Annual Conference of the North American Chapter of the Association for Computational Linguistics, Companion Volume: Demonstration Session Michael Johnston editor Fred Popowich editor Association for Computational Linguistics Boulder, Colorado conference publication ji-chen-2009-cross https://aclanthology.org/N09-5001/ 2009-06 1 4