@article{3542,
      author       = "Sigmark, Ejnar and Andersson, Axel and XIII. Congress of
                      the International Society for Photogrammetry, Helsinki,
                      1976. Commission III",
      title        = "Block-Triangulation by the Independent Three-Dimensional
                      Method  ",
      year         = "1976",
      note         = "1 sv.",
}