@article{JMLR:v21:18-447,
  author  = {Dongruo Zhou and Pan Xu and Quanquan Gu},
  title   = {Stochastic Nested Variance Reduction for Nonconvex Optimization},
  journal = {Journal of Machine Learning Research},
  year    = {2020},
  volume  = {21},
  number  = {103},
  pages   = {1--63},
  url     = {http://jmlr.org/papers/v21/18-447.html}
}