@misc{indiciae8b1f5c78df40,
  title = {Propulsive options for a manned Mars transportation system},
  author = {Braun, Robert D. and Blersch, Donald J.},
  year = {1991},
  url = {https://ntrs.nasa.gov/citations/19910048765},
  note = {Source identifier: 19910048765}
}