Xiang Chen 0016 Lei Li 0040 Ningyu Zhang 0001 Chuanqi Tan Fei Huang 0002 Luo Si Huajun Chen Relation Extraction as Open-book Examination: Retrieval-enhanced Prompt Tuning. 2443-2448 2022 SIGIR https://doi.org/10.1145/3477495.3531746 conf/sigir/2022 db/conf/sigir/sigir2022.html#ChenLZTHSC22