Combining Lexical and Grammatical Features to Improve Readability Measures for First and Second Language Texts Michael Heilman author Kevyn Collins-Thompson author Jamie Callan author Maxine Eskenazi author 2007-04 text Human Language Technologies 2007: The Conference of the North American Chapter of the Association for Computational Linguistics; Proceedings of the Main Conference Candace Sidner editor Tanja Schultz editor Matthew Stone editor ChengXiang Zhai editor Association for Computational Linguistics Rochester, New York conference publication heilman-etal-2007-combining https://aclanthology.org/N07-1058/ 2007-04 460 467