@misc{indiciaea8977a9c12f2,
  title = {Minimal Surfaces Spanning Closed Manifolds.},
  author = {R Courant and N Davids},
  year = {1940},
  doi = {10.1073/pnas.26.3.194},
  url = {https://pubmed.ncbi.nlm.nih.gov/16588337/},
  note = {Source identifier: 16588337}
}