@misc{indiciaeb26239a4ed98,
  title = {Testing for long-term stability of two-color geodimeters; January 1986 to August 1989},
  author = {J. O. Langbein},
  year = {1990},
  doi = {10.3133/ofr9091},
  url = {https://pubs.usgs.gov/publication/ofr9091},
  note = {Source identifier: ofr9091}
}