Helpfulness-Guided Review Summarization Wenting Xiong author 2013-06 text Proceedings of the 2013 NAACL HLT Student Research Workshop Annie Louis editor Richard Socher editor Julia Hockenmaier editor Eric K Ringger editor Association for Computational Linguistics Atlanta, Georgia conference publication xiong-2013-helpfulness https://aclanthology.org/N13-2011/ 2013-06 77 83