@article{ef21withbellswhistlespractical,
  title = {EF21 with Bells & Whistles: Six Algorithmic Extensions of Modern Error Feedback},
  author = {Ilyas Fatkhullin and Igor Sokolov and Eduard Gorbunov and Zhize Li and Peter Richtárik},
  year = {2021},
  eprint = {2110.03294},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2110.03294v2},
}