@misc{indiciaef78249d094e1,
  title = {The Helen Planitia region of Venus in four map sheets; 1, Radar image map of the Helen Planitia region of Venus; 2, Radar image and shaded relief map of the Helen Planitia region of Venus; 3, Altimetric radar image map of the Helen Planitia region of Venus; 4, Topographic map of the Helen Planitia region of Venus},
  author = {Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey},
  year = {1998},
  doi = {10.3133/i2477},
  url = {https://pubs.usgs.gov/publication/i2477},
  note = {Source identifier: i2477}
}