@misc{indiciae3556f3b01012,
  title = {Trajectory optimization using regularized variables},
  author = {Lewallen, J. M. and Szebehely, V. and Tapley, B. D.},
  year = {1969},
  url = {https://ntrs.nasa.gov/citations/19690000667},
  note = {Source identifier: 19690000667}
}