@misc{indiciae27ab2e561d8e,
  title = {Mars Surface Tunnel Element Concept},
  author = {Jefferies, Sharon and Rucker, M. and Howe, S. and Howard, R. and Mary, N. and Lewis, R. and Watson, J.},
  year = {2016},
  url = {https://ntrs.nasa.gov/citations/20160002226},
  note = {Source identifier: 20160002226}
}