@misc{indiciaed0be9bce9acb,
  title = {Advanced Transportation System Studies. Technical Area 3: Alternate Propulsion Subsystem Concepts: Executive Summary - Volume 1},
  author = {Levack, Daniel J. H.},
  year = {2000},
  url = {https://ntrs.nasa.gov/citations/20000044647},
  note = {Source identifier: 20000044647}
}