Overview of the CCKS 2019 Knowledge Graph Evaluation Track: Entity, Relation, Event and QA. - Xianpei Han; Zhichun Wang; Jiangtao Zhang; Qinghua Wen; Wenqi Li; Buzhou Tang; Qi Wang; Zhifan Feng; Yang Zhang; Yajuan Lu; Haitao Wang 019; Wenliang Chen; et al. (CoRR, 2020)