@misc{indiciaecc27e18f1e17,
  title = {Orbital transfer vehicle concept definition and system analysis study, 1986. Volume 9: Study extension results},
  author = {Kofal, Allen E.},
  year = {1987},
  url = {https://ntrs.nasa.gov/citations/19890004083},
  note = {Source identifier: 19890004083}
}