@article{30680,
      author       = "Verstelle, Th. J. and International Union of Geodesy and
                      Geophysics. Eleventh General Assembly, Toronto - 1957",
      title        = "Standard Sheets of Hyperbolic Patterns for Survey Use  ",
      year         = "1957",
      note         = "Geodesy. (Electronic Survey Systems.), 1 sv.",
}