@misc{kriebel2026_critical_wave_sparse_control_quadratic_growth,
  author = {Alec Kriebel},
  title = {Failure of strong quadratic growth in unregularized sparse control of a critical wave equation},
  year = {2026},
  doi = {10.5281/zenodo.23358014},
  url = {https://doi.org/10.5281/zenodo.23358014},
  note = {Unrefereed preprint, version 1.0; manuscript and declared Zenodo date 14 October 2026; Zenodo record created 14 October 2026 UTC}
}