@misc{indiciaeb79b26567bde,
  title = {Empirical estimates of cumulative refraction errors associated with procedurally constrained levelings based on the Gaithersburg- Tucson refraction tests of the National Geodetic Survey},
  author = {R. O. Castle and T.D. Gilmore and R. K. Mark and R.H. Shaw},
  year = {2012},
  doi = {10.1029/gl012i005p00239},
  url = {https://pubs.usgs.gov/publication/70013031},
  note = {Source identifier: 70013031}
}