@misc{indiciae04b0ce15d4bb,
  title = {Head-mounted spatial instruments: Synthetic reality or impossible dream},
  author = {Ellis, Stephen R. and Grunwald, Arthur and Velger, Mordekhai},
  year = {1988},
  url = {https://ntrs.nasa.gov/citations/19890002813},
  note = {Source identifier: 19890002813}
}