@misc{indiciaef6489b4fe8ad,
  title = {A modified perturbation method for solving optimal control problems with state variable inequality constraints},
  author = {Tapley, B. D. and Williamson, W. E.},
  year = {1971},
  url = {https://ntrs.nasa.gov/citations/19710063911},
  note = {Source identifier: 19710063911}
}