@article{Ludewig2014,
  author    = {Matthias Ludewig},
  title     = {Vector fields with a non-degenerate source},
  journal   = {Journal of geometry and physics},
  volume    = {79},
  pages     = {59 -- 76},
  doi       = {10.1016/j.geomphys.2014.01.014},
  year      = {2014},
}