@misc{indiciae9c39ea1041e1,
  title = {RayGUI; a graphical user interface for interactive ray-tracing (rayinvr)},
  author = {Jeremy Loss and I.A. Pecher and Uri S. ten Brink},
  year = {1998},
  doi = {10.3133/ofr98203},
  url = {https://pubs.usgs.gov/publication/ofr98203},
  note = {Source identifier: ofr98203}
}