@article{663,
      author       = "Agarwal, Colonel G.C. and XIII. Congress of the
                      International Society for Photogrammetry, Helsinki, 1976.
                      Commission IV",
      title        = "Accuracy of Spot Heights and Determination of Minimum
                      Contour Interval for Plotting  ",
      year         = "1976",
      note         = "1 sv.",
}