@article{unbiasedestimationoftheolscovariance,
  title = {Unbiased estimation of the OLS covariance matrix when the errors are clustered},
  author = {Tom Boot and Gianmaria Niccodemi and Tom Wansbeek},
  year = {2022},
  eprint = {2206.09644},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2206.09644v1},
}