An Investigation into the Validity of Some Metrics for Automatically Evaluating Natural Language Generation Systems Ehud Reiter author Anja Belz author 2009-12 text journal article Computational Linguistics continuing MIT Press Cambridge, MA periodical academic journal reiter-belz-2009-investigation 10.1162/coli.2009.35.4.35405 https://aclanthology.org/J09-4008/ 2009-12 35 4 529 558