@article{Tu2014,
  author    = {Rui Tu},
  title     = {Fast determination of displacement by PPP velocity estimation},
  journal   = {Geophysical journal international},
  volume    = {196},
  number    = {3},
  pages     = {1397 -- 1401},
  doi       = {10.1093/gji/ggt480},
  year      = {2014},
}