@misc{indiciae33c5a260b0dd,
  title = {Transcontinental geophysical survey (35°-39° N) magnetic map from 87° to 100° W longitude},
  author = {Isidore Zietz and J.R. Kirby},
  year = {1968},
  doi = {10.3133/i534a},
  url = {https://pubs.usgs.gov/publication/i534A},
  note = {Source identifier: i534A}
}