@article{21346,
      author       = "Schwahn, W. and Elstner, C. and Savin, I.V. and
                      Intern.Symp.Geod. a. Phys.Earth,Potsdam, 1988",
      title        = "On the modulation of the M2 gravity tide  ",
      year         = "1988",
      note         = "Liter. - l tab. - Obr.příl. - 1 sv.",
}