@misc{indiciae0ae1a1983e68,
  title = {Maps showing geology, oil and gas fields and geologic provinces of the former Soviet Union},
  author = {F.M. Persits and G. F. Ulmishek and D.W. Steinshouer},
  year = {1999},
  doi = {10.3133/ofr97470e},
  url = {https://pubs.usgs.gov/publication/ofr97470E},
  note = {Source identifier: ofr97470E}
}