@misc{indiciaecaf0eee2c698,
  title = {Equivalence relations for the classification and solution of optimal control problems.},
  author = {Cullum, C. D. and Polak, E.},
  year = {1966},
  url = {https://ntrs.nasa.gov/citations/19670034537},
  note = {Source identifier: 19670034537}
}