@misc{indiciae4a3f70fe0d5a,
  title = {Prolongation structures of nonlinear evolution equations},
  author = {Wahlquist, H. D. and Estabrook, F. B.},
  year = {1975},
  url = {https://ntrs.nasa.gov/citations/19750033973},
  note = {Source identifier: 19750033973}
}