@misc{indiciae0490a5599ed2,
  title = {Conjugate points on a limiting extremal.},
  author = {M Morse},
  year = {1976},
  doi = {10.1073/pnas.73.6.1800},
  url = {https://pubmed.ncbi.nlm.nih.gov/16592324/},
  note = {Source identifier: 16592324}
}