@thesis{Tielen2021a,
  title         = {P-multigrid methods for Isogeometric analysis},
  author        = {Roel Tielen},
  year          = {2021},
  url           = {https://doi.org/10.4233/uuid:8445e901-e31e-4602-8630-5b39a3de7ff6},
  school        = {Delft University of Technology},
  type          = {doctoral thesis}
}