@misc{indiciae39c1d6839c08,
  title = {Mars Surface Tunnel Element Concept},
  author = {Rucker, Michelle A. and Mary, Natalie and Howe, A. Scott and Jeffries, Sharon},
  year = {2016},
  url = {https://ntrs.nasa.gov/citations/20150019637},
  note = {Source identifier: 20150019637}
}