Constructing Corpora for the Development and Evaluation of Paraphrase Systems Trevor Cohn author Chris Callison-Burch author Mirella Lapata author 2008 text journal article Computational Linguistics continuing periodical academic journal cohn-etal-2008-constructing 10.1162/coli.08-003-R1-07-044 https://aclanthology.org/J08-4005/ 2008 34 4 597 614