@article {2009.07258, archivePrefix = {arXiv}, eprint = {2009.07258}, primaryClass = {cs.IR}, author = {Zhi Zheng and Kai Hui and Ben He and Xianpei Han and Le Sun and Andrew Yates}, title = {BERT-QE: Contextualized Query Expansion for Document Re-ranking}, year = {2020}, url = {http://arxiv.org/abs/2009.07258} }