@misc{Doe2023,
  doi = {10.48550/ARXIV.2301.11992},
  url = {https://arxiv.org/abs/2301.11992},
  title={Data sparse multilevel covariance estimation in optimal complexity}, 
  author={Dölz, J},
  publisher = {arXiv},
  year = {2023},
  eprint={2301.11992},
  archivePrefix={arXiv}
}