@article{18081,
      author       = "Hofmann-Wellenhof, R. and Lichtenegger, H. and 20th General
                      Assembly of the IUGG, 11 - 24 August 1991, Viena",
      title        = "Methods of Resolve GPS Phase Ambiguities  ",
      year         = "1991",
      note         = "Abstr. - Liter.",
}