@article{20426,
      author       = "Sneeuw, N.J. and 20th General Assembly of the IUGG, 11 - 24
                      August 1991, Viena",
      title        = "Non-Singular Cross-Track Derivatives Using Rotated
                      Spherical Harmonics  ",
      year         = "1991",
      note         = "Abstr. - Obr.",
}