@inproceedings{shi2020text,
  title={Text CAPTCHA is dead? a large scale deployment and empirical study},
  author={Shi, Chenghui and Ji, Shouling and Liu, Qianjun and Liu, Changchang and Chen, Yuefeng and He, Yuan and Liu, Zhe and Beyah, Raheem and Wang, Ting},
  booktitle={Proceedings of the 2020 ACM SIGSAC Conference on Computer and Communications Security},
  pages={1391--1406},
  year={2020}
}