“…Some leverage semi-supervised learning techniques to resolve the training data insufficiency issue, including self-learning (Sun et al, 2018;Mao et al, 2020) and co-training (Chen et al, 2018). (iii) Another line of research seeks to retrieve auxiliary or indirect supervision signals from profile information or side features of entities, such as entity attributes (Sun et al, 2017;Trisedya et al, 2019;Pei et al, 2019), literals (Wu et al, 2019(Wu et al, , 2020bLiu et al, 2020), free text , pre-trained language models (Yang et al, 2019;Tang et al, 2020) or visual modalities (Liu et al, 2021). Due to the large body of recent advances, we refer readers to a more comprehensive summarization in the survey (Sun et al, 2020c).…”