@article{Morel:4269,
      author        = "Morel, L.  and Durand, F.  and Moudni, O.  and Pottiaux,
                       E.  and Follin, J.M.  and Durand, S.  and Van Baelen, J. ",
      title         = "{Global validity and behaviour of tropospheric gradients
                       estimated by GPS}",
      month         = "Jul",
      year          = "2019",
}