@article{JMLR:v26:24-0059,
  author  = {Ilyas Fatkhullin and Igor Sokolov and Eduard Gorbunov and Zhize Li and Peter Richt{{\'a}}rik},
  title   = {EF21 with Bells & Whistles: Six Algorithmic Extensions of Modern Error Feedback},
  journal = {Journal of Machine Learning Research},
  year    = {2025},
  volume  = {26},
  number  = {189},
  pages   = {1--50},
  url     = {http://jmlr.org/papers/v26/24-0059.html}
}