@article{21345,
      author       = "Avaste, O. and Willmann, Ch. and IUGG - IAG, 15th General
                      Assembly Moscov, 1 - 14 August 1971",
      title        = "On the Metod of Determination of the Optical Depths of
                      Noctilucent Clouds  ",
      note         = "1 sv.",
}