Tianxiu Xie Hong Zhang Yiwei Feng Jing Qi Chennan Guo Gangqiang Yang Keke Gai Cross-Chain-Based Distributed Digital Identity: A Survey. 525-534 2022 SmartCom https://doi.org/10.1007/978-3-031-28124-2_50 conf/smartcom/2022 db/conf/smartcom/smartcom2022.html#XieZFQGYG22