@misc{indiciae494c76f6e022,
  title = {User oriented, interactive Multics computer programs to create grid cell, contour, and perspective maps using Surface Display Library},
  author = {R. K. Mark and E. B. Newman},
  year = {1981},
  doi = {10.3133/ofr81513},
  url = {https://pubs.usgs.gov/publication/ofr81513},
  note = {Source identifier: ofr81513}
}