@article{li2021weakly,
  title={Weakly convex optimization over Stiefel manifold using Riemannian subgradient-type methods},
  author={Li, Xiao and Chen, Shixiang and Deng, Zengde and Qu, Qing and Zhu, Zhihui and Man-Cho So, Anthony},
  journal={SIAM Journal on Optimization},
  volume={31},
  number={3},
  pages={1605--1634},
  year={2021},
  publisher={SIAM}
}