Double Layered Learning for Biological Event Extraction from Text Ehsan Emadzadeh author Azadeh Nikfarjam author Graciela Gonzalez author 2011-06 text Proceedings of BioNLP Shared Task 2011 Workshop Jun’ichi Tsujii editor Jin-Dong Kim editor Sampo Pyysalo editor Association for Computational Linguistics Portland, Oregon, USA conference publication emadzadeh-etal-2011-double https://aclanthology.org/W11-1824/ 2011-06 153 154