@article{13864,
      author       = "Leitinger, R. and Putz, E. and Inst. Metrolog. Geoph. -
                      Univ. Graz and 19. IUGG - Vancouver, Aug. 9-22, 1987",
      title        = "Ionospheric Refraction Errors and observables  ",
      year         = "1987",
      note         = "Obr. a tab. v textu. - Liter., 1 sv.",
}