Exploring Surface-Level Heuristics for Negation and Speculation Discovery in Clinical Texts Emilia Apostolova author Noriko Tomuro author 2010-07 text Proceedings of the 2010 Workshop on Biomedical Natural Language Processing K Bretonnel Cohen editor Dina Demner-Fushman editor Sophia Ananiadou editor John Pestian editor Jun’ichi Tsujii editor Bonnie Webber editor Association for Computational Linguistics Uppsala, Sweden conference publication apostolova-tomuro-2010-exploring https://aclanthology.org/W10-1910/ 2010-07 81 82