@article{19088,
      author       = "Welch, R. and XIIth Congress of the International Society
                      of Photogrammetry in Ottawa 1972",
      title        = "Modulation Transfer Functions  ",
      year         = "1971",
      note         = "Reprinted from "Photogrammetric Engineering" 1971/ 3, s.
                      247-259, 1 sv.",
}