Clustering to Find Exemplar Terms for Keyphrase Extraction Zhiyuan Liu author Peng Li author Yabin Zheng author Maosong Sun author 2009-08 text Proceedings of the 2009 Conference on Empirical Methods in Natural Language Processing Philipp Koehn editor Rada Mihalcea editor Association for Computational Linguistics Singapore conference publication liu-etal-2009-clustering https://aclanthology.org/D09-1027/ 2009-08 257 266